Visions of the Universe
Visions of the Universe ISP 205
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Miss Claudine Cruickshank
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This 144 page Class Notes was uploaded by Ms. Mckenzie Labadie on Saturday September 19, 2015. The Class Notes belongs to ISP 205 at Michigan State University taught by Staff in Fall. Since its upload, it has received 99 views. For similar materials see /class/207732/isp-205-michigan-state-university in Integrative Studies Physical at Michigan State University.
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Date Created: 09/19/15
Measuring Radial Velocity The Doppler effect th mwzvelengthxs Spennxnafgalaxyntxest gt1 M was 2m Mmemwm Wm Fur vvelunty uf emmer a an an m an 430 w e velunty ufwave mommy we M v 5 g X c g Galaxymavmgnwny 3 Dapplermxflunly 5 an wq w Me 07 m7 500 measures velun mwwv alung lme ufsxght mg 1514 Emma s Law 1929 Measuring Distances 3 Seenglsls mm 1929 39 mm 1m usngedshl s Measure radial velocityv from Doppler shi Hubble s Law v Ha a HV is called Hubble constant 21am eneeessm a manna Ve ncny kmsec WWW m g AW smmmsewe Specmmnfgalaxyatnn N M MMWHW Measure Dupp er smmmm arms mn urabsurptmn hnes Redsm z Am vc F39mg v mm Hubb e s Law Had distances distances An nouncements this page posted as part of lecture notes on Angel Homework 7 due late at night Monday April 23 630AM Apr 24 Homework 8 now available on Angel Due late at night Friday April 27 630AM Apr 28 Final exam info 810PM Thursday May 3 in Natural Resources 158 SW corner of Farm Lane amp Wilson About 5055 questions About half on material since Midterm 3 including my lecture on March 29 Questions provided by Prof Smith amp Baldwin I will only ask about material in lectures or on homework Sample questions at wwwpamsueducoursesisp205sec1 Study guide coming next Wednesday About half on material up through Midterm 3 Questions provided by Prof Loh Use same study guides as for midterms already available on syllabus page on Angel The Expanding Universe 39 39 39 39 39 Cosmological principle Universe looks the same from any point 20000 Expanding Universe 0000 a Hubblejs LaW Scale Factor Rtirne Rt U 39 2 3 5 Pro er DistanceRt X comovin distance Proper D1stance gt p g Velocity gt RU increased by factor 2 The Evolving Universe 30000 open See Fig 1616 Velocity gt 100 200 300 400 500 Proper Distance gt Hubble s law V H0 1 d distance v velocity travel time n T 20000 b E at 3 s 392 3 8 3 closed Proper Distance gt 12 s 1 1 g Time gt T2 T07 Past Present Future The Evolv1ng Universe open See Fig 1616 n Slope H0 g at 3 E 3961 2 I 8 I m I closed I I I f2 1 0 l4 T LT3 Time T2 Past Present Future 1 H0 approx1mate age of Unlverse A Canon Ball 39 h I h I ht ve10c1ty w change in tim e 1 Ah E At 0 51 slope of curve time V escape ZGM R height critical cume canon ball has exactly escape velocity We only know the slope of the red arrow H0 A Canon Ball A Ems time A Canon Ball A Ems ZGM R V escape V escape R A Canon Ball height time Velocity gt 0 0 100 200 300 400 Proper Distance gt Hubble s law V H0 1 d distance v velocity travel time The Expanding Universe See Fig 1616 an 500 Scale of universe H Time Li T1 T3 T2 T0 Dani pmennf Fl m Ira The Expanding Universe 0 Individual galaxies do not get stretched 0 Light waves do get stretched 9 redshift Redshift 9 scale factor Rt at time light was emitted The Expanding Universe 0 Individual galaxies do not get stretched 0 Light waves do get stretched 9 redshift 1 1 2 z HEW old 1 old old 2 Rt 0101 lnzw l 2 At lookback time corresponding Now to redshift z Redshift 9 scale factor Rt at time light was emitted Clicker Question The highest redshift galaxies and quasars found so far have redshift z 6 How many times closer together was all of the material in the universe when the light from them was emitted At lookback time corresponding Now to redshift 2 9097 05014 A 1 Rt 2 old in 12 The Evolving Universe 19271997 version nnPn Time I mm The Evolving Universe 19271997 version See Fig 1616 open Formerly concentrated in a tiny volume Scale of universe I Kinetic energy vs gravitational r attraction 1 LEE Time T253 9 Curvature of space To Past Present Future 9 Evolution Energy balance Curvature Future kinetic gt gravitational negative open kinetic gravitational at critical kinetic lt gravitational positive closed Which Universe do we live in open 3 R0 1 Z 5 g 8 m closed I LiTkTGT Time a To 2 Past Present Future R on lookback time39 39 Lookback time distance traveled by photon 9 which model of universe is correct Which Universe Do We Live In Type Ia Supernovae Neighbor star dumps too much mass onto aw 39te w Collapse to neutron star Supernova explosion Type Ia Supernovae as standard candles Always happens when mass goes just past limit for white White dwarf dwarfs at center of Supernova always has same acqe on luminosity disk L Get distance from Flux 2 41tr Which Universe Do We Live in Distance light travel time lo kback time At man What we can measure for supemovae Redshift Distance Rn 11z a 1 1 VET Tlme4 T2 To DAM Dmum umra Scale of universe I Which Universe Do We Live in kback time At Distance light travel time lo nnen What we can measure for supernovae Redshift Distance Scale of universe R R0 l1z 1 Time A Age of Universe 137 billion years Clicker Question gt 07 0 Universe Do We Live in kback time At What is implied by the upward bend in curve 4 light travel time lo Gravity is the only Scale of universe Fi decrease in th e future l 5v v L Universe 137 billion years The Cosmological Constant Dark Energy Einstein s static universe Cosmological constant balanced gr Einstein My greatest blunder Acts as force pushing things apart Gets stronger as separation increases What is it Nobody knows Is it really a constant Nobody knows Cosmic Microwave Background rst Galaxizs 1 Second 300000 Vans 1 Billion Yul Tll Planck Formation Galaxy NOW llme Formallol l ll39l allol39l Decouplll lg of OMB Hot Cool 1032 K 109 K 3000 K 3 K Background First Galaxies 2 g E U 5 Eu 2 00 3 Z Cosmic Microwave 0 1039quot Sec 1 Second 300 000 Years 1 Billion Vears Ti Planck Formation Gal EXY Now time ofH He Li Formation In ation Decoupling of CMB Hot Cool 1032 K 109 K 3000 K 3 K High density Low density Cosmic Microwave Background Hotter 0 Hydrogen ionized Universe opaque Photons travel only short distances 0 Absorbed reemitted by free electrons T 3000 K DE 021 11 I1g 137 billion yrs ago Universe 300000 yrs old 0 Hydrogen becomes neutral p e H Universe becomes transparent Photons decouple from matter continue in whatever Cooler direction they were moving What Powers the Sun 0 Need to provide 4x1026 watts lt 2x1033 grams mass of Sun gt 45 billion years age of Earth 0 Nuclear lSlOl l reactions 4 x 1H gt 4He neutrinos energy Hydrogen 1H Helium 4He Elemmn 10quot 7m gt 2 Proluns 2 Neulmns Computing the structure of the sun For every point in the Sun we want to compute temperature 2 Pressure g 39 composition density g 3 a composition e imam 000 0 02 03 04 I15 06 01 08 09 LEI RadiantRa energy generation energy transport mechanism density We can write 4 equations expressing the following ideas The Sun is a gas The sun is neither contracting nor ure expanding The sun is neither heating up nor cooling down Specify method of energy transfer Sunspm Ami are xquot region 1 Granulation 0 39 03 Ll 02 DJ 04 05 06 07 08 09 Iquot Radiu nl eg 1 21le 0 Low density and pressure 10394 01 X values But hot 5 8000 K 0 Granules in photosphere Tops of convection currents Transparent gas layer reaches 20003000 km above photo sphere T 500010000 K 0 Photosphere point we can no longer see through chromosphere o T gt 10000000 K 0 Very low density 103910 bar 0 Heated by magnetic energy 0 Several X diameter of photosphere Magnetic Fields Control Much of Sun s Surface Activity Force Motion of a charged B mag eld round a magnetrc velocity x r Magnetic 7 p QWQQ QQJQQQSEQJ Q QSquot quot B Electron field lines of I r 9 force g Sunspots 3 Cooler regions where lines of force enterleave surface Solar Wind 0 Charged particles with greater than escape velocity escaping through holes in magnetic eld Prominences 0 Charged particles following magnetic lines of force Flares 0 Magnetic field lines short out Huge burst of charged particles 1122 yr Solar cycle 0 Due to winding up of Sun s magnetic eld The Sun s magnetic field Here s What we observe about stars The MassLuminosity Relation H t The HR Diagram 0 Luminosity Temperature Radius 1000 000 390 Higher stars 39 s Luminosuy LSM 3 1 102 E 5 1 10392 Main sequence is wmedwans v I l I a mass sequence Speclralclass o B A F G K M Su acelempevalurem 25000 10000 6000 3000 Colorindex 04 00 06 14 MAIN SEQUENCE Stars convert H into He in their cores Predicted paths of stars on HR diagram i39 1 1 9f 17 120 x10 111 mm 155 larm355 5 quot702 x m 21 main 55 Hence 2b 10 q 1m Glants E 1109 E E 3 15 Sular masa 339 1 D39 4 x mg 1 739 111539 1 301m mass Hburnlng in shell 15 551m mass 10 l P M 7 25000 130013 45300 Su ane temperalure Elij see gs 1210 1212 Star clusters are snapshots of stellar evolution WW M41 2 mm 103 yrs old V 39 A m W i 47 Tucanae l m 3 01 yrs old g 39 e I 4 4xin mum mm mm sum m Surface temperatur T 6000 3000 To see how it all works look at http Wwwmhhe r i All stars in a given cluster formed at same time But with a wide range in masses Main sequence turnoff stars just finishing main sequence evolution nnwhtml http WWWparnsueducoursesisp205sec3hrmpg Stellar Evolution Here Evolution through nuclear burning Minitial gt 2MO Nuclear burning all the way to iron Minitial lt 2M0 Nuclear burning shuts off after He ash Mass loss Planetary nebulae Eta Carinae Supernovae There Final state M nal gt 3M0 Black hole 14 lt Mfinal lt 3M0 Neutron star M nal lt 14MO White dwarf Formation of stars and planets Molecular gas clouds 0 Up to 105 MCD 100 s of LY in diameter High density by interstellar medium standards Shielded from UV radiation by dust atoms are combined into molecules 0 H2 and also CO plus other more complex molecules Preferred place for stars to form 0 In spiral arms of our Galaxy Some examples of star forming regions discussed in class 0 Orion Nebula M 16 Pillars of Creation Star formation disks around stars Planets form in these disks Planets around other stars 0 Over 100 known 0 Usually detected through their effect on motion of the parent star Possible sites oflife in our Solar System Elsewhere The Milky Way Gas large fraction of stars in thin disk 1000 LY thick Spiral structure globular V39 c lusters Spherical halo 150 globular clusters Spherical distribution of stars Nuclear bulge Sun s location V dilsk l 39 10001ightyears Fig 141 23000 lightyears globular cluslers Atoms Absorb amp Emit Light Spectra The wavelength of the light that an element emits or absorbs is its fingerprint Atoms emit and absorb light First Test is Thurs Feb 1St About 30 multiple choice ques ions 0 e require working with models such as phases of Ven zodiac Fig 212 Click on Study Guide amp 2005 Test on Syllabus Class of 30m is not on test Homework Higher of 2 attempts is used How to study Identify Big Ideas Practice models amp examples Do 2005 test Go over homework amp clicker questions Go to office hours Brian homas after each class in atrium Missouri Show Me Club Mon 29m 700800pm 1415 BPS Homework 3 is ready on angel Due at 600am on Tues 30 Light is the atom s fingerprint Spectroscopy Spectrograph Instrument that measures how bright the light is at each individual wave ength Prism spreads light by color Grating does the same Each element emits a unique set of spectral lines its fingerprint A spectrum of starlight reveals what elements are in the star Prism Detector measures brightness of light at each point in vertical direction Light is the atom39s ngerprint A hut gas emits mm univ at certain discrete Waveiengths Hvdravenemns mamasan WWW 1E4Dnmbiue M znmmaid m mmquot henween am mg m mm mm atwweienv 5 Cumras1 A biackubiectemitsiium at aiiwaveienuths maranue pm 4 mm Light is the item39s ngerprint ts mm W a ce am mm Magnum Mr ms um 31 ammo a mm m mum mAc H mm mm hm wading cm A m abrenemns um um r u waveienv hs m What 5 he absorpuon spectrum or H39s A Hm gasemnsugm Recau a penecw WW a cenam mscvele b ack mectemnsa WWW my spechum 5 H Hymmm h a mackataH 3553quotij 483mm ngmsv SYSQLHWE HS L mwumuwumaen H m Hm mm mm a 5mm quot mm m wave env h What 5 me absorpuon spectrum of H7 vebnmhswheve MM Recau a penecw H emu mm m a su n Wm a Ves emssmnspewum b Na Mmmmun mawave env h Astrophysical examples Absorption Lines a a Spectrum of a starl I a I ll mi rm 1 l Ff 1 l 39 rah R Planetary nebula IC 418 shell if frat E r T Ganthuum Howrath Of gas blown Off Star LTr I Absurp gn line I q u TH 3399 LHaEua Elana EEE El TIBEHEI Wavelength I i i t 39139 l l I lil l quotlquot i I i I i i Ti 7 I as 5 E quotT 2 quot 55 1 2 X x N Spectrum of 5 E 79 Planetary nebula A AI L4 AA A L l 14 LA 4000 5000 6000 7000 8000 9000 Wavelength How do atoms absorb amp emit light In an atom electrons orbit a nucleus In H one electron orbits nucleus How do photons quanta of light interact with atoms Need to explain why atoms emit amp absorb photons at discrete wavelengths Fig 54 How do atoms absorb amp emit light In an atom electrons orbit a nucleus Key idea Energy A photon carries energy Electron in orbit has energy because it is moving and it is pulled by nucleus Mental image Electron is in a hole because of electric pull of nucleus It takes energy to climb up the hole E eV Energy of electron in Hydrogen 1o 12 14 5 10 15 r is distance between electron amp nucleus How do atoms absorb amp emit light In an atom electrons orbit a nucleus Key idea Energy A photon carries energy Electron in orbit has energy because it is E eV QZ How much energy does electron need to climb from Lev 12 a 14eV b 10eV c 3 eV Energy of electron in Hydrogen moving and it is pulled by 2 nucleus Mental image Electron is in a hole because of electric pu ol nucleus It takes energy to climb up the hole 10 12 l4 ri distance between electron amp nucleus Levell HOW d0 atoms Q3 An atom with electron in L3 absorb amp emit emits photon Where does energy of photon come from a Electron supplies energy by dropping to a lower level b Electron supplies energy by Key idea Energy 39 A phOton carries energy going to a higher level 39 EleCtrO in orbit has c Nucleus gives up some energy energy because it is d Energy is created moving and it is pulled by nUCleUS E EV Energy of electron in Hydrogen When atom absorbs 2 photon energy of photon promotes electron to higher energy Niels BOhr S Visible emission line of H quantization Red line isjump 3e2 Cyan line isjump 4e2 Blue line isjump 5e2 Electron cannot jump from level 4 to level 25 and emit some green light Big question in 1900 Why does hydrogen emit amp absorb light at discrete wavelengths at discrete energies Bohr s quantization rule Electron can only be in a level for which angular 2 momentum Ln h h is Planck s constant n1234etc These are levels in plot 10 Bohr s rule showed path tol2 quantum mechanics E ev Energy of electron in Hydrogen l4 Other lines of H Visible emission line of H Red line isjump 3e2 Cyan line isjump 4e2 Blue line isjump 5e2 Q4 Why did we not see lines that can account for jump 21 a Thisjump cannot occur 2 b Light of this wavelength is 4 ultraviolet and not visible to 6 the eye E ev Energy of electron in Hydrogen 8 C Light of this wavelength is infrared and not visible to 10 the eye 12 14 471 Other lines of H 7 n 7 v v quotI 1 Balmer series Transitions between level 2and higherlevelsare 1 r visible Lyman series 39 y 1ehigher is in ultraviolet Pasohen series Brackett ii is 4ehigher is in infrared Birth of Science Tycho Brahe observes motion of planets Homework 2 is ready Due at 600am on Tues d Kepler discovers 3 laws 23 Jan of motion for planets 39 0 angelmSUedU39 9 to LessonsgtHomeworkgtHo Newton discovers laws meworkz of motion for all objects lit Brahe 15461601 Kepler 15711630 Newton 16431727 Questions on reading 1 When Kepler was a college student the most accurate description of the motion of planets uses the terms a Velocity position amp acceleration b Circular orbits c Elliptical orbits On Urniborg Tycho measured positions of the planets for 20 years Highly accurate amp reliable Accuracy limited by human eye not by Uraniborg Brass azimuthal quadrant 65 cm radius ca 1576 instruments Superseded only with telescopes Tyco measured amp compensated for instrument flexure the biggest error Great quadrant 1582 DRAN S Mv39 SIVE TXGHONICVS Kepler analyzes Tycho s data Kepler was Tycho s assistant 20 yrs data on planetary motions Tycho tried to fit data with Ptolemylike model Kepler analyzed the data Found 3d orbits from 2 d positions in the sky Concentrated on orbit of Mars Had to subtract off Earth s imperfectly known orbit Discovered 3 laws which describe the motions of the planets 1 ill V Brahe 15461601 Kepler 15711630 Their meeting at Benatek in Czechoslovakia on 4 February 1600 Tycho de Brahe and Johannes Keplerus cofounders of a new universe met face to face silver nose to scabby cheek Tycho was fiftythree Kepler twentynine Tycho was an aristocrat Kepler a plebian Koestler The Sleepwalkers p302 Kepler s First Law Orbit of a planet is an ellipse with the sun at one focus Definition ofan ellipse Distance between planet amp focus 1 distance between planet amp focus 2 is the same for the entire orbit This was an unexpected result in Kepler s time Ellipse is a simply defined shape not any shape The motion ofthe planets must have a deeper cause If the sun is at a focus it must affect the planet s m Semimajor Sun at one focus Semimajor axis Min Earth s orbit is nearly circular Kepler s Second Law The linejoining the planet and the sun sweeps out equal areas of space in equal amounts oftime Planet moves more slowly when it is far from sun more rapidly when close to sun Kepler s Laws Law 1 Orbit of a planet is an ellipse with the sun at one focus Law 2 The linejoining the planet and the sun sweeps out equal areas of space in equal amounts of time 2 V nter is a few days shorter than summer for us in the northern hemisphere Therefore Earth is at A B C or D in January Sun D HMm a s o P2a3 Kepler s Third Law P period of orbit in years a semimajor axis of orbit in AU Average Earthsun distance is 1 AU The Motions of the Planets Ptolemy Copernicus Kepler 140 AD 1543 1609 More accurate description of data Kepler s 3 Laws Orbit of a planet is an ellipse with the sun at one focus The straight line joining the planet and the sun sweeps out equal areas of space in equal amounts of time 0 P2 a3 But why These are descriptive laws but there must be deeper reasons for the planets to do this Isaac Newton One of the great geniuses of the millennium Invented calculus mathematics of change Invented mechanics the description of howthings move Principi39a 1687 Discovered Law of Gravity Kepler s laws can be derived from Newton s laws But Newton s laws are a general descriptions of a far wider range of phenomena universally valid except on the smallest or largest scales or in extreme situations strong gravity high velocities 39 2 16431727 Natural motion for Newton amp Aristotle Natural motion is motion that needs no explanation the object naturally moves that way Aristotle For heavenly objects natural motion is motion in a circle with the same speed For base objects natural motion is rest A bookfalls offthe table and comes to rest on the floor This needs no explanation because rest is the natural state Newton Natural motion is moving at the same speed in the same direction Newton s First Law In the absence of a force an object moves at the same speed In the same direction Q3 A book falls off the table and lands on the floor For Newton what is natural The book is on the floor The book is halfway to the floor The book isjust starting to fall I push the book off the table F19 F75 The Sun March 2 Test 2 is not graded How does the sun yet produce energy See me if you need Inside the sun provisional grade immediately We know the most about one star 0 We know the most about the sun because we can see surface details Other stars are points of light Magnetic elds wind ares Seismology gt sound waves probe interior How do we know Make observations Make theories Compute models 0 How does the sun produce energy Question rst asked in 19 11 century Theories failed o DO models agree with Bethe found answer in observations 193 Os Repeat Process o Today new questions of detail How does the sun produce energy Lord Kelvin William Thomson in Glasgow Scotland in 1860s Observations Sun 2x1030 kg produces 4x1026 watts for 45 Byrs Batteries chemical reactions 0 5 wattsbattery gt 8x10 batteries required Battery lasts 40 hours Sun can shine for 100 years Far too short Kelvin has a better idea Contraction of the sun Led him to maintain that solar system is 100Myrs old which is incorrect Gravitational contraction Converts gravitational potential energy into kinetic energy Kinetic energy in a gas heat Collisions between atoms convert heat to light KelvinHelmholtz contraction To provide 4x1026 watts sun must contract by 40 meters per year 40m x 2000 years of observations undetectable Sun shrinking by half gt shine for 80 million years 800000 X better than batteries amp chemical reactions But not good enough We need gt 45 billion years 60 times longer 69 How does the sun produce energy Crisis No solution with physics of 193911 century Einstein s new theory 1906 Energy mass X speed oflight2 Energy can change into mass and mass can change into energy Changing a little mass produces a lot of energy Speed oflight c 300000 kms Nitrogen in air moves at 0 1 kms Air in blast furnace moves at 0 2 kms Chemical reaction Chemical v10k ms two H atoms make H molecule Em1000000000 c2 One part in billion of mass gy disappears and changes into ener How does the sun produce energy Crisis No solution with physics of 19th century Einstein s new theory 1906 E m c2 Energy mass X speed oflight2 Energy can change into mass and mass can change into energy Speed oflight c 300000 kms Q A hydrogen atom falling from 1 AU hits the sun at 300 kms How much of the mass is converted into energy a 100 b 11000 c ll000000 Nuclear fusion 4 x 1H gt 4He neutrinos energy 4 hydrogen nuclei fuse One helium nucleus is produced Q Why does RHS have less mass than LHS a 5295 You are not weighing the energy Helium is a lighter gas Some of the mass changed into energy The balance is faulty 4Hev LW Lighter by 07 Sun produces energy by nuclear fusion 4 x 1H gt 4He neutrinos energy 4 hydrogen nuclei fuse One helium nucleus is produced 07 ofmass becomes energy Sun can potentially produce 0 007 X 2X1030 kg X 3X108 rns2 10 S Joules of energy Sun can shine for 1045 Joules4X101 5Js100 Billion years Sun will actually last 10 Byrs because 10 of mass is used before sun becomes a dead star 4Hev LW Lighter by 07 Jovian Jupiter like Planets Homework 4 Due Thurs 26 Feb 600am Test 2 is Tues March 3 Covers material through terrestrial planets 217 gtr g 91 gm n Kai goa as o 3 983 H33 93 3 0 pa Kt Practice test link on syllabus Missouri Club is 700pm Mon March 2ml Summarizing Q s What is the structure of Jupiter amp how is it different from Earth s Done 2 Why is the interior of Jupiter hot Done 3 Why does Io Jupiter s satellite have Volcanoes 4 Why are the inner moons irregular in shape and the big moons spherical Done 5 Why do the Jovian planets have rings Roche limit For a moon in orbit around a planet P2 a3 39 rfferent parts of extended body have different orbital periods So body tends to be torn apart More important close in But selfgravity tends to hold it together More impo ant far out Roche s limit is Where these two opposing effec are balanced 13 RRoche 25 pplanetpmoon Rplanet where p density kgm3 and Rpm radius ofplanet If density of planet amp moon are the same then RRnche 25 Rplanet Saturn s rings 126 top amp bottom Views 70000 km wid only 100m th Bottom View showing the light that is not reflected by the rings Note the Cassini division Colorenhanced top View showing spokes of unknown origin What are the rings made of Ice dust Dynamic Ephemeral Bodies Fig 827 Waves in the rings Probe Cassini s passage through the rings July 1 2004 The braided F ring Prometheus 102 km long part 0 a ring Ring particles move according the Kepler s Laws except for the presence of moons The biggest force is gravity ofplanet Moon add a tiny but important force Many small moons found in rings Their gravitational interaction shapes the rings Gap moons pull on particles and disrupt their orbits Cause gaps in rings Pairs of moons can shepherd rings particles together Bigger moons cause large gaps For particles at a certain location on every other orbit Mimas is in the same position Mimas pulls the same way and clears out the particles from that position There is no material in the Cassini division All 4 Jovian planets have rings Uranu see Fig 829 Jupiter s ring Imaged by Voyager 3 Galileo Location of the rings Dots are moons Lines amp bands are rings We c a 39 A r New I I Fla el Txda sums slammy mm Roche 1am 4 The large moons were made by collecting smaller moons Why can t the material in the rings collect to form large moons a There is not enough material b The rings are too thin c The gravity ofthe planet 1d tear the moon apart d The rings are not made of sticky material Roche 5 limit and the Rings Large objects cannot form in this region or get broken up even if they do form Jamey Samquot Umnm mama mm gt l su nzs Roche limit Formation of the Solar System Questions Why are rocky planets close to the sun Why is solar system a disk How did the planets form Asteroids Meteorites fossils from the birth of the solar system How old is the solar system Terrestrial amp Jovian Planets Why are the planets near the sun dense rock and the farther planets less dense like water Jupiter 1 3 gmcm3 Mercury 54 gmcm3 Collapse of the Protosolar Cloud Thermal history of the Solar System I am a hydrogen molecule in the cloud that will become the sun My energy is kinetic due 70392 to motion and potential m 0 4 due to gravity 70 6 EnergyKEPE 08 I KE is proportional to V2 I PE depends on distance r to center of cloud When I fall from r 30 AU Neptune to r 1 AU Earth my KB and temperature increases by a factor 30 fl welliemaralJammno iemm g tempmm increases by a factor 30 If temperature of material falling to Nepture is 30K the temperature of material falling to 1 AU is 900K Temperature of plot is not so steep Material cools too 39 Q Can SiOZ sand and Water condense at lAU when Eanh formed A YY B YN C NY DNN 39 Same question for Uranus 1500 Melal oxldes eg N203 lrorrnmkel alloy Slllcale mlnsmls 1000 Ivan uxlde F20 OHvIne FSQSlCh and MnglDJ Temperarure lKl Tliollte F25 50quot Hydrated mlnerals Cumaming H20 Temperature K Water leol Ammonia th Methane cm Nlmv39l mt line was and Beyond nest mu nyaogen compounds roars and condenses mums n h dragon mmnds stay mus WhenI fall from r 30 AU Neptune tor 1 AU Earth my KE andtemperature increases by a factor 30 Iftemperature of material falling to Nepture is 30K the temperature ofmaterial falling to 1 AU is 900K Wllhln Ihi saw nebula saw 0 ma mamtm ls hymogen Fig 620 and quotstrum gas Ihnldoesr mndnnsa anywhere Metal oxides teg Argon tvorwi ckel alloy Slllcale mrnsmls f tooo 2 Ivan uxrde F20 v 3 Ohms thgsio and Mgzsm E E 5 amp Tliolile F25 E 500 ydrated minerals 1quot Containing H20 Ware mm M V leOl ania NHJ ethane cm 0 Evaporation emperature Giants vs Terrestrials Inner solar system I Lighter elemenw evaporated away I Planetesimals contained only heavy elements I Growth stopped at Earthsized planets I Continuing impacts With planetesimals altered the planets I s m I Reversal of Venus rotation etc I Dumped much of atmospheres onto planets Outer solar system I ces as Well as silicates available for solid bodies I Larger protoplanew res e I These cores able to attract surrounding H amp He gas in order to build giant planets I Gravitational eld of giant planets perturbed orbiw of remaining planetesimals I Most comets ejected into Oort Cloud Why is the solar system spinning amp disk shaped Rings and moons System Skater represents protosolar system Kepler s Law of Equal Areas Conservation of Angular Momentum L m r v r is distance to rotation axis measured perpendicular to rotation ax15 V is Speed Of mating mOtiOn 0 Q If s a 39 39 own cloud collapses I u If skater pulls arms in cloud toward disk skater spins a faster b shrinks horizontally skater same c slower spins faster Q If material falls toward sun material spinsii Same foils Atmosphere of Earth amp Venus Test1 Processes that shape eanh Losing gases in atmosphere Gaining gases in atmosphere Venus Goldilocks Paradox Test 1 Score Rank How am I doing Good job ifl am in the top quartile rank lt60 score gt24 Need improvement if I am at the bottom rank gt220 score lt15 Cuts are on Angel Test 1 only represents 16 of course grade Howto do better on the next test Aim to understand ideas Purpose of homework amp practice test is to check your understanding Think about key idea for each question Ideas are important answers are not Do not memorize the answers Models are important answers are not Do not memorize the answers Do not memorize questions For some questions the ideas are the same as on homework or practice test but the wording is differen Atmosphere of planets loss of gases Planets formed from the same material but now have very different atmospheres Earth has little helium Jupiter has a lot of helium Mercury has little atmosphere Think of gas molecules as baseballs moving and colliding How do baseballs escape from the earth s gravity Average kinetic energy of gas molecule Important Hotter means more KE 3k2 Temperature kinefic enerQY KE 12 mass speed2 Not Important 3k2 Q Oxygen molecules m32 in the air move at an average speed of 300ms Helium m4 moves at an average speed of a 40 ms b 300 ms gt c 850 ms cl 2400 ms Baseball can escape if Kinetic Energy gt Potential Energy 39 Speed2 gt ZGMEarthREarth Escape speed from earth is 11000 ms How can helium escape How can helium escape from earth By chance a helium atom gets much more speed than the average and esca es Average 850 m Very rare 1200 Is On earth each molec second Q 81 It is easier to lose a ligh as 82 It is easierto lose gas from a hotter plane 3 It is easierto lose gas from a more massive p et a T T T b F T T c T F T d T T F e Two are false eta new try every billionth of a Flve ways Almospheres Lose Gus lherma escape solar wind svipp wng nnuensallon emphanc gases Ink space cwyummrumm mmvamMnnuAmnwnhy Three Ways Ammheres Galn Gas avaDoralbnxub mllm bavomum by m crometeurila smav wmd andn highsnelgy pholans am am mmzmvm mm nusan mm Life amp the Earth s Atmosphere Life started in CO2 atmosphere roughly 4 billion yrs ago Life initially only in sea converted CO2 to oxygen through photosynthesis The released oxygen was swallowed up in interactions with surface material until 2 billion yrs ago After 2 billion yrs ago oxygen able to build up in atmosphere o geological activity buried much ofthe free carbon Atmosphere then converted to today s mix 78 nitrogen 21 oxygen 1 everything else Free oxygen ozone protection from ultraviolet light land animals lLife converted Earth s atmosphere from CO2 to N2 02 Venus is too hot for life What went wrong Description of Venus Atmosphere of Venus Why did Venus get too hot even though Earth its twin remained temperate Venus according to Botticelli Venus our sister planet V 7 1970 viii 1511 1975 Venera Lande rs 13gt 14 5011 Venera 1112 1978 USSR samples basalts Venera 1314 1981 39 7 BEHEF Q 14 UEPHEDTKH HFII39IH RH ECCP H LlElKC The View from Venera l4 Radar Map of Venus Made by Magellan orbiter in 1991 93 Blue lower Brownred higher The surface of Vnus 74 Impact craters age dating of surface only 15 as many craters as lunar maria 39 Magellan Radar Oldest terrain only 800 million yrs old Imaging compare to 38 billion yrs on Earth Constant resurfacing by volcanic action but appears to have ceased 500 million yrs ago Volcanic Activity on Venus Radar Imaging 100 m resolution SifMons a shield volcano 500 km diameter x 3 km high l Lava 110w Pancake volcanoes due to Comm a collapsed dome very thick lava over a magma chamber Interior Structure Tectonics Similar to Earth lron core 3000 km in radius Molten mantle Crust Lakshmi Planu Hilly area on Ishtar No plates as on earth But much shearing compression and stretching of crust by convection currents in man e Has pushed up continents Aphrodite and Ishtar Rift valleys and cracks Ridges amp ad s The Atmosphere of Venus Surface Pressure 92 x Earth s C 2 Surface Temperature 482 C N2 melting point of lead 327 A Sulfuric acid cloud layer at 3060 km Earth 003 Some Surface Temperatures in F Mercury Mariner 10 800F Venus Mariner 2 Venera landers 900F Hell Revelations 218 832F But the fearful and unbelieving shall have their part in the lake which burneth with fire and brimstone boiling point of brimstone sulfur 832F Goldilocks 1 Venus istoo hot Mars is too cold Why isthe earth just right not too cold and not too hot Venus istoo close to the sun and Mars is too far This is part of the answer Reflected light is 2 d ingredient Greenhouse effect is 3rd ingredient History is 4 relative to Wo GH Table from Rampino ampCaldeira 1994 Ann Rev Astron ampAstrophys 32 p83 Greenhouse effect Greenhouse effect Sunlight is absorbed by the planet s surface Surface ernrts infrared radiation infrared radiation is absorbed by co2 amp H20 and reradrated rnanytrrnes before it escapes into space co2 amp H20 acts like a blanket V thout the greenhouse effect earth would be frozen Mars has a small greenhouse effect Why did Venus evolve to have such a large greenhouse e Why did greenhouse run amok on Venus When the sun becomes brighter the earth becames warmer More evaporation 2 more rain More rain 2 loss ofmore 002 sequestered in rock Less 002 2 less greenhouse effect Less greenhouse 2 Earth cools lessening effect of sun brightening Which is not a possible reason why greenhouse ran amok on Venus Too hot to rain Type of rocks cannot sequester 002 There is no plate tectonics Venus was born without water 9957 Why did greenhouse run amok on Venus Deuterium Normal H has l proton in nucleus Deuterium D has 1 proton amp l neutron Mass of n amp p same Q1 Suppose I had a pound of normal hydrogen I trade a deuterium for every hydrogen atom How much would I have A 1lb B 2b C 12 lb D 4 lb Q2 At the same temperature which gas moves fastest and is more likely to escape A normal H B deuterium C H20 D DHO Key observation of water Earth s ocean has 100000 X more than Venus atmosphere Key observation on deuterium abundance On earth HD5000 On Venus HD50 Q3 Which hypothesis is wrong a Venus formed without much water b Venus lost its water Venus lost its water Venus is hotter because it is closer to sun Water was in atmosphere Ultraviolet light broke water into oxygen and hydrogen Hydrogen escaped No rain 2 no way to get rid of C02 Models show Earth will suffer same fate if sunlight increases by 40 CO2 cycle will not be sufficient to keep Earth temperate AmmsAbmxbampEmHLm 29Jan Spectra Spectrum of thermal radiation The wavelength of the light that an element emits or absorbs is its fingerprint Atoms emit and absorb light First test is Thurs Feb 5 About 30 multiple choice questions Some require working with models such as phases of Venus amp zodiac Fig 212 You may use one cheat sheet 812 x 11 front and back Click on Study Guide amp 2005 Test on Syllabus Material covered on Q2 3 amp 28 from 2005 will not be on the es Missouri Show me Club Tues Feb 3 700800pm room 1415 Covers material through Tues 27 Jan Spec oscopy Spectrograph Instrument that measures how bright the light is at each individual wave ength Prism spreads light by color Grating does the same Detector measures brightness of light at each direction BlackBod Spectrum 000 K slay h s K lntens39tyisamrmntnfmdiz nn 0 550 Emmad Ernn39nfzrmpu39secnnd Empaztureisin Kelvin degezs 2 ma 3000 Kstar E 3 10 E 02 l0quot l W Y Wavelength nm Q A hot object emits more 39Em gl infrared radiation than a cool Q There is light in a dark room The Dbl501 An example fohis is eason is a Q amp S a It is impossible to cover thewindows b P amp R completely R amp s c b My eyes see blotchy light in a dark room d R ampQ c Everything in the room emits in 39ared Q What trend WDUId you light which our eyes cannot see observe as an object heats up BlackBody Spectrum The spectrum has a characteristic shape Sharp drop towards higher energy Slow drop towards lower ener y The wavelength ofthe peak of in m 390 the spectrum is at shorter Wavelength nm 9 wavelength and higher energy Ener Peak wavelengt given by Men s Law for homequot 0131505 1W 27mm KI T hotter objects have peak at smaller 9 Total energy emitted per s perunit surface area is given by Stefan Boltzmann Law E 5 T3 Increase with temperature is very steep factor of2 for a factor of12 in T Light is the atom s fingerprint Each element emits a unique set of spectral lines its ngerprint A spectrum of starlight reveals what elements are in the star A hot gas emits light only at certain discrete wavelengths Hydrogen emits light at 6563nm red 4861nm cyan 4340nm blue 4102nm violet etc No light in between Other elements emit a different pattern of wavelengths Contrast A black object emits light at all wavelengths In a range Demo Is this H 41014340 new 6563 nm I ll39 nm nm Light is the atom s fingerprint A hot gas emits light only at certain discrete wavelengths Hydrogen emits light at 6563A red 4861A cyan 4340A blue 4102A violet etc No light in between 6563A 656 3nm Contrast A black object emits light at all wavelengths in a range Sodium Hydrogen Calcium Mercury Neon Emission spectra of hot gasses Mystery element Each element emits a unique set of spectral lines its fingerprint A spectrum of starlight reveals what elements are Prism in the star Detector measures brightness of light at each point in vertical direction What is the absorption spectrum of H A hot gas emits light Recall a perfectly only at certain discrete black object emits a wavelengths thermal spectrum ls H Hydrogen emits light at black at all 6563nrg geg 455SI1nm wavelengths C an nm ue Eliy02nm violet etc No Q1 W Uld Ydmge light in between gas absorb th at o Other elements emita 500nm different pattern of a Yes emission spectrum wavelengths is black at that wavelength b No its emissivity is 0 at that wavelength mot 4340 4551 new l39lle l39l39 HlTl l lm What is the absorption spectrum of H At wavelengths where Recall a perfectly H emits light it also black object emits a absorbs light thermal spectrum ls H black at all wavelengths Q1 Would hydrogen gas absorb light at 500nm mm 4340 4qu 5553 a Yes emission spectrum m m quotm is black atthat ntofblack by l 39ength b No Its emisswity Is 0 at that wavelength mini 43m 485i 6553 rim rim rim nm Astrophysical examples Absorption Lines m w w Nquot Spectrum of a star i39Vv n l I I 39 Planetary nebula IC 418 shell 1 mm of gas blown off dying star mm 0 Emission Lines quot 5 i Spectrum of Planetary nebula J m 7m m Wavelength How do atoms absorb amp emit light In an atom electrons orbit a nucleus In H one electron orbits nucleus How do photons quanta of light interact with atoms Need to explain why atoms emit amp absorb photons at discrete wavelengths 1m 4340 43131 mm mm mm Fig 54 How do atoms absorb amp emit light In an atom electrons orbit a nucleus 5 N cncrgy a ctecnsr 1n Hydro Key Idea Energy quotquot quota quot quot121 quot 3 A photon carries energy 399 Electron in orbit has rt energy because it is E moving and it is pulled by ucleus Mental image Electron is in a hole because of electric pull of quot4 nucleus It takes energy to Cl39mb up the hOIe r is distance between electron amp nucleus How do atoms absorb amp emit light In an atom electrons Q How much energy does orbit a nucleus electron need to climb Key idea Energy from Level 1a2 a 14eV A photon carries energy b3 109V 03 3 eV Electron in orbit has energy because it is moving and it is pulled by 71 nucleus 1 Mental image 1 Electron is in a hole 7 because of electric pull 039 i nucleus It takes energy wr distance between electron amp nucleus to climb up the hole 42 ievi Energy at electron n nyareeen a m How do atoms Q An atom with an electron in L3 emits photon Where does absorb amp emlt energy ofphoton come from Key idea Energy 39 A Photon carries energy going to a higher level 39 EleCfl39Dn in orbit has c Nucleus gives up some energy energy be ause it is d Energy is created moving and it is pulled by nucleus 3 leV Energv a electron n Hydrogen 39 E 39 V V 39 39 V 39 7 1395 7 V 39 V When atom absorbs 7 electron to higher energy The End of the Universe Continued expansion forever we think 10quot sec Planck Time 103938 7 103932 sec In ation 103932 sec 7 104 yrs Radiation Era 1047 10 yrs Stellar Era lNow 714x 101EI yrs 101 7 1037 yrs Degenerate Era 1037 101quotI yrs Black Hole Era gt101m yrs Dark Era Extremely speculative See S191 amp Telexcope magazine August 1998 Degenerate Era 39 101 71037 yrs 39 Almost no further radiation from 39 cold dark universe 39 But 39 Occasional collisions between new lowmass stars 10 to 100 in existence per galaxy at any given time 39 Occasional collisions of degenerate stars supernova 37 Th End Produm M Inquot Years or 5mm Evaluunn Black Hole Era 39 10377 101 yrs 39 Degenerate stars have all disappeared through proton decay maybe p e nenninos gammarays No more a orns Dark matter previously swept into degenerate stars and annihilate 7 39 Only black holes are left 39 But black holes also evaporate Hnwkmg mmnnon very slow conversion of gravitational energy back to particles or photons Dark Era 39 Essentially nothing le except hugely redshi ed CMB photons What s outside the Universe 0 Other universes not intersecting with our Universe 0 Some magic numbers 0 At t 1 second our Universe defined by 39 Ratios of 7 Energy Density MatterKineticenergyCosmolgicalconstantenergy 7 Numbers of particles PhotonsNorrnalmatterDarkmatter 39 Amplitude of density uctuations 10395 Imprinted by Planck Time ratios of physical constanm 39 Example electrostatic force 103 7 x stronger than gravitational force 0 Different values in other universes Anthropic Principle our particular universe is suitable for us to live in because otherwise we would not be alive to know about it Good book Before the Beginning by Martin Rees Galaxies 39 100000 LY 39 Composed of 100 billion stars or more 0 Main types are 39 39 Ellipticals Sun Buge Disk 39 Spirals 39 Regular spirals l 39 Barred spirals ars Irregul Glob clusterov Our galaxy the Milky Way u m u IS a sp1ral w1th a weak bar 1m Inm Hm 0 Mass of galaxies dominated by quot39 Dark Matter n39 39 Detected by studying motions of stars around galactic centers Announcements Homework Final Exam Set 8 HOW Open 0 Monday December 13 due late at night Friday Dec 10 3AM Saturday Nov 11 0 Set 7 answers on course web site 0 810 PM PM in the evening I I 0 1n the usual classroom Natural Resources 158 Counts as 15 midterrns 70 questions 0 23 over material since Midterm 3 0 13 over earlier material 0 reworded midterm questions 0 a few new general questions 0 a few about telescopes Review for Final RightNaw Course Evaluation httpsrateyourclassmsuedu Spiral Arms Density wave 0 Spiral arms have higher density u m quotquotquottqlfn39 t than space between arms an in 0 Excess gravitational attraction I H slows down gas stars when they m pass through spiral arm in course of their orbim spiral arms are atrafficjam But also some effect due to differential rotation natural tendency of big starforming regions to just get wound up into spiral shapes Galaxy Formation TopDown Model Collapse 9 rotating disk Halo Globular clusters amp halo stars formed during collapse Once formed stars don t collide BottomUp Model Time 9 Now Small structures form rst Dwarf galaxies Globular Clusters Galaxies grow by cannibalism Ellipticals formed by mergers of spirals The Cosmic Distance Ladder Parallax 0 Out to 65 LY Calibrate luminosities of Pulsating Variables Use pulsating variables to map rest of Milky Way and out to M31 In M31 Measure luminosities of Brightest stars 10000 LG Brightest globular clusters 100000 LG Brightest H 11 regions 100000 LG Etc 9 can now measure distances to more distant galaxies 9 Velocitydistance relation for distant galaxies i v v War zcanc war 7 Velocity gt an on ma scn Distance gt Hubble s Law V Hod Galaxies all recede from each other 9 Scale of the whole universe is expanding The distribution of matter l mu mn L ocal Supercluster m n f quot w w Structure upon Structure Location Fraction of critical density The Cosmic Web Structure determined by evolution of dark matter Gas within galaxies 0 001 Total normal matter 0022 Big Bang Nucleosynthesis predicts 003 Gas in galaxy clusters 0 003 Stars within galaxies 0 004 Gas between galaxy clusters 0 014 Dark Matter 0 3 About 90 of all matter is dark matter Relativity Special Relativity The Principal ofRelativity The laws of physics are the same in all inertial reference frames The constancy 0fthe speed oflight Light travels through a vacuum at a speed c which is independent of the light source General Relativity The Principle oquuivalence Can t tell difference between gravity amp acceleration or between freefall amp no gravity So any experiment should give same answer in either case Predicted and then observed effects of Special Relativity E mc2 Time Dilation Gravity Upwards acceleration no gravity quot x 5 a J v r Falling due No gravity to gravity Proofs of General Relativity I Rapid precession of Mercury s orbit y I Everything nds shortest path I Phenomenon known before in spacetime I GR olfered the explanation Curved Space I Bending oflight rays passing near Sun I First measured in 1919 I Photons light nd shortest pa cause they move the fastest I Time dilation in gravitational elds Measured using real clocks on Earth I Gravitational redshi in strong gravitational elds I Observed in spectra ofwhite derfs Mun i n l asars High density 9 Strong Gravitational Field I Large redshi 9 large distance And also 9 Black Hole F U4 d2 Locatedin centers of 41rd2 F L galaxies i Hapymfd Escape Velocity I Measured ux distance 9 huge luminosity 21 13 quot 1 0f Up to 1000 x luminosity ofan entire galaxy of stars g quot5 A v 26M 7 eitng 1 R Schwarzschild radius vmqe 6 speed of light 2 e f 2GM L RS 2 c Some luminous quasars vary in few days 9 same size as solar system Accretion Disk Nearby Galaxies with Mini The EX p an d i n g U n iv e I S 6 forms around Quasars in Center T gt Black Hole Small fraction of nearby galax1es have 45 a I huge out ows of particles moving at T W Hubbles Law nearly speed of light gt 39 Galax1es all recede from us Giant blobs of a Velocity proportional to distance 6 charged particles Tm V HO d Big Elliptical seen at radio Galaxy seen wavelengths in visible light from Black Hole stars Massive black holes in most nearby galaxies but not currently accreting gas We are unlikely to be at exact center The Source of the L m h quot Sity 9 Scale of the whole Gravitational Potential Orbits of stars 9 universe is expanding Energy million solarmass Matter falls onto black hole at center of Milky Way Distance Rtime x comoving distance accretion disk Galaxy Disk heats up amp glows P2 a3m1 m2 Summary How do we know the universe is expanding from a very much smaller size nnPn Hubble s Law Everything is moving away from everything else Seal of universe R Cosmic Microwave Background CMB 1 Universe used to be much hotter than it is now 9 it has 39 I 14 changed and evolved k k V To 2 Dan prnennf Fllhirn Time V Escape height 9 A Canon Ball A Canon Ball height 9 V Escape height 9 A Canon Ball The Expanding Universe Which Universe Do We Live in 1 39 I 39 39 Distance light travel time 9 lookback time At I I I an I an O I I 3 I I I a I I m l m L CD I I 39 39 39 39 What we can g E dlstance 9 I measure for I Hubble s law 5 1 supernovae 5 2 2 V Ho d 55 Redshift gs 1 distance 0 Distance 39 39 39 39 39 39 3950 11z v velocity I xi 1 travel time 0 L I I L 1 Li Time LET Time H0 TOTE TUTE Dani Prnennf ll l llr Dani Prncnnf Elmira The Accelerating Universe Structure in the Cosmic Microwave Background Distance light travel time 9 lookback time At What does it tell us Sound waves permeated universe just before decoupling of CMB Linear size of largest structure Acceleration due to Dark men Energy pushing outwards cc speed of sound X age of universe at that time a What we can cg 2333c to slurfarce erlmttmg e en s s on on measure for p g y acceleratmg 3 cosmologlcal model open suPernovae39 3 9 Angular size depends t Redshlft g on cosmological model 3 at 395 D1stance Ra 11z 1 u closed I a quot 39 ltEs quotquot39 yquot quotI r 739 I T l37 b11110n yrs 1 I 17 a he Pas Prawn qum I35 cf Prnennf Fl m Ir Wh is the solar s stem s innin amp disk sha ed ASte rOIds February y y p assertion 32232242231235 larger radius and smaller and therefore increases velocity of rotation her rotational velocity Recap SS formation 6 Test 2 Skater represents Mon Feb 28 ASterO39dS are Old protosolar system Covers Age of solar system Keplers Law Oquual 6 questions from Test 1 Added to score of Test 1 Telescopes Solar system Format similarto Test 1 Missouri Club Areas Conservation of Angular Momentum L m r V r is distance to rotation axis V is speed of rotating motion oupyrgnmzmrnarsa a Mi 9 If skater pulls arms in Fri 900 1415 aterjumps amp lands Fri last 10 minutes of class Emmi Sth nks k t cloud collapses toward Homework 3 closes 3am 8220 a Y S a er Spms disk skater spins a Mon faster b same c slower Why IS the solar system spinning amp disk shaped La WWWquot md Flg 6 27 Asitconlracts the cloud heats mg I I con t d it in the productm X v X r Bringing in her arms 9 S gr n8 U a ran a u H grav 3quot extended arms mean decreases her radius larger radius and smaller and therefore increases velocity at rotation her rotational veiocity flattens and stains faster becomin oi dust and gas Sun will be born in center Planets will form in disk Warm temperatures allow only melaliroclr quotseedsquot to condense in Inner solar system a spinning dis 3 Skater represents protosolar system Hydrogen and helium remain gaseous but olher materials can condense into Edd temperatures u w 7 1 llawquotseeds to solrd seeds lorbulldingplanets p mamabundamice in outer solar system If cloud shrinks toward axis horizontally cloud spins faster Real cloud can only spin so fast because gravity must hold gas in orbit Iv 39 Terrestrial planets are built from metal and rock Solid seedsquot collide and stick together The seeds of 39ovian Larger ones attract others with their planets grow large gratuity growan hlgger still enough to attract 0 hydrogen and helium 9 I a 39 a Museum 39 39 lti h i 39 Cloud can shr1nk alonngmm v u 333 3193223 7 r pane moons ormrn sp1n aX1s w1thout butt1ng disks ofduslandgas Ihal surround the planets agalnSt angl ar Solar rgrind lotions remaining gas U Terrestrial ianete remain In 0 In Ersie lat Spacer quot 1 Inner at Jovian lane remain momentum Cloud can inouregpggrarsystem Leftovers lrom the atten39 9 39g formation process become asteroids metalrrooki and ND 0 3 3 comets mmlly ice Progressive Buildup of the Planets Before the Sun started to produce its own energy Small dust grains condensed from nebula mmsized Clumped up into planetesimals 10 s of km in diameter comets and asteroids Crater formation rate I Hypothetical cratering maximum Cratering of highlands Imbrium and Orientale impacts Formationofmaria rapidly accreted further planetesimals 39 Run away growth into protoplanets larger bodies had more gravitational attraction collected lots of smaller bodies a few MercuryMarssized objects Recent craters Tycho Copernicus l l 4 Time before present billions of years i Impacts heated interior of growing planet 3 2 1 differentiation in molten interiors Giants vs Terrestrials In inner solar system Lighter elements evaporated away Planetesimals contained only heavy elements Growth stopped at Earthsized planets But continuing impacts with planetesimals altered the planets Earth s moon Reversal of Venus rotation etc Dumped much of atmospheres onto planets In outer solar system Ices as well as silicates available for solid bodies Larger protoplanets These cores able to attract surrounding H He gas in order to build giant planets Gravitational eld of giant planets perturbed orbits of remaining planetesimals Most comets ejected into Oort Cloud Somehow governs existence of asteroid belt The End Game The Sun became a star Solar wind high velocity particles streaming outwards from Sun Blew away the remaining H He gas Left just protoplanets remaining planetesimals to finish up their interactions Timescale to this point only 10 million years Asteroids 91 Small rocky objects in orbit around the Sun Sizes up to hundreds of km 26 known ones with sizes gt 200 km 250000 currently have designations estimated gt 1 million asteroids lt 1 km in size But total mass probably less than mass of Moon Jupiter main asteroid belt Jupiter 7 The Asteroid Belt semimajor axis 2 2 3 3 au Between orbits of Mars and Jupiter Includes 75 of known asteroids Mostly orbiting sun in same direction of planets and in plane of solar system Fig 9 3 TI O an Astero1ds J up1ter prevented planet from forming 0 In same orb1t as Jup1ter but leadmg or tra1l1ng Jup1ter average distance semimajor axis in AU 0 Gaps 1n astero1d g i 2 3 4 5 E by 60 o o o belt correspond 25039 i i i i i i i i 1 Grav1tationally stable pos1tion tooresonances mg l i Q 1 g 1 w1th orb1tal 1 391 Ti j l E y Trojans Troians per1od of J up1ter E 1500 N 3335 mm 0 21 resonance E I Asteroid every 2 E 1000 sou i g a D i I i I 1 I i i J i 0 Similar case exists for Mars Jupiter 0 i 2 3 4 5 e r a a mu iEiSM every T T 0mm period Wears also perhaps for Venus and Earth period Eaiiii Mars F 9 4 Jupiter Also a few aster01ds are known 1n outer solar system 1g Asteroids seen from Galileo Most Asteroids are Dark Where Different Types of Asteroids are Found Gaspra 19X12X11 km Rotation 7 hrs Orbit 1 4 AU Composition Stype differentiated primitive L a D i Low re ectivity 3 4 Primitive bodies C type Few craters chemically unchanged since recently formed from initial formation of Solar System Gaspra compared to 50 Percent of total IIIIIIIIII Phobos amp Diemos the 2 breakup of larger body Most are carbonrich Ctype moons of Mars A180 Stony Stype 9 o o 0 1 g A g Ida and Dactyl dark carbon compounds m1ssmg Distance from Sun AU f 52 km long A few metalrich Mtype Hg Rotation 4 5 hrs Dactyl 0 Especially re ective at radar wavelengths Mars Asteroid belt Jupiter orbit 1 8 AU Ida S llt e com anion Remnants of a differentiated body Compos1tion S type P Collisions with Earth giant ironnickel deposits Member Of group resulting from breakup Of heavier body 0 Heavy cratering happened long ago 433 Eros Near Earth asteroid 113 to 178 AU Stype 35 X 15 X 13 km Size of Lansing 0 Q1 Hypothetical discovery NEAR nds Eros has signi cant amounts of water Would this be a You would we1gh 3 oz on Eros little surpr1se bag of potato ch1ps 20 h d 139 39t a39 Yes mp spee 1m1 b NO NEAR spacecraft orbited for 1 year then landed Feb 2001 NEAR found that Eros is not differentiated Colors show elevation bluelow 124 km orbit Q1 Hypothetical Near Earth asteroid 113 0 Q2 If that were an actual Near Earth asteroid 113 discovery NEAR finds to 178 AU discovery how would to 178 AU Eros has signi cant 35 x 15 x 13 km size of you change the theory of 35 x 15 x 13 km size of amounts of water Lansing Eros formation Lansing Would this be a 0 You would weigh 3 oz on 39 Q3 WhiCh 1116013 can be 0 You would weigh 3 02 on surprlse Yes Ems disprOVed Eros Q2 If that were an actual discovery how would you change the theory of Eros formation a Form near Jupiter then collide to put it near earth b Formed as a comet collided c Formed in astreoid belt collisiion li J Homework 5 is due Wed 24 March at630 m One answer is wrong See email OBAFGKM extra credit Angel LessonsgtExtra Credit Due 1155pm 31 March Answer on Q36 on Test 2 was It will be regraded Final exam new later time 410 Giants are dying stars white re dea stars Why does the sun die Whatwill the sun become when it dies HertzsprungRussell HR Diagram Stars AAldebaran BBarnard s Star CCapella DRigel What do you need to know about stars to answer the next 4 questions10 1 Pick one correct ans a Hotplate model of star b Model ofthe solar interior c How to read HR Diagram d Spectrum of black body e Energy generation in the sun Which is the hottest star Which is the smallest star Which is the biggest star 104 If stars AD replaced the sun would people be able to live in Michigan Luminosity Lsun Ghmpuhimnlsllm 39 mm J F P N NN b NYNN 0 B A F C NNYN Spectral class d NNNY 25000 10000 6000 3000 e NNNN Temperature K see Fig 1110 J F P N HertzsprungRussell HR Diagram Stars AAldebaran BBarnard s Star CCapella DRigel need to know about 639 a 39m 2 S e Energy generation in the sun X Which is the hottest star Which is the smallest star Which is the biggest star If stars AD replaced the sun would people be able to live in Mic 7 Luminosity Lsm crmararm r 5mm m 104 quotquotr higan A F G YNNN Spectral class b NYNN 25000 10000 6000 3000 c NNYN Temperature K d NNNY e NNNN see Fig 1110 Giants are dying stars white dwarfs are dead stars Evidence on giants from star clusters Compare members ofa population Twin study All stars in a cluster are born at once Formation time is the collapse time of the cluster which is very short I am a G star like the sun I have 100000 fraternal twins some weighing 30 times my mass some 110 of my ass M80 Pleiades Not all fainter stars were observed 39 For 5 star ctusters mam sequence extends to coo er stars beyond observatwons In what ways are HR diagrams o Perseus Pleiat es Hyades amp NGC18 39 e 5 Hottest stars m Perseus are hotter than hottest stars m P e ades uminosity solar units b Most stars are on the mam sequence NGC188 has smaH range of ummoswty Some ctusters have grants LIICtmIE mu 0 o nx Parser A 1 1 I NGC BE 30000 10000 6000 3000 sudace temperature Kelvm 3 Luminosity gt 25000 10000 5 Temp suture 3000 HR Diagrams of star clusters Q2 There are no A stars in M80 because a they neverformed b they died and disappeared all stars became redder as they get older they are too faint to see 0 9 Is there life out there 184 SETI Search for ExtraTerrestIial Intelligence Listen for radio transmissions from other civilizations Seems plausible f there are lots ofhabitable planets out there vmmm cm 7 3n 3 39smm m 1 No contactsyet after several decades I Background noise level Looking for Terrestrial Planets in Looking for Terrestrial Planets in Habitable Zonequot Habitable Zonequot Nottoo hot Nottoo hot Nottoo cold l Nottoo cold Just ri ht Just ri ht 9 Very hard to see 9 Sun a blllluntlmes bilghtevthan Eanh Need enough eed enough heavy elements to eavy elements to make terrestrial l Wm wmve 5 make terrestrial planets 5 quotquot Equot Ianets Known Planets outside our Solar System see Extrasular Planets Catalugue http VWWV ubsprn frEncyclcatalug htrnl Total as utMamhi znna 342 planets 29m planetary systems 37 multiple planet systems Detection methods Wobble methud 316 planets 58 Transits Gravitatiunallensing 8 Directlmaglng ll Timing ufpulsars 7 The Wobble Method the Dupplertechnique SPeedPenml gt Size mm a Then a p K207151370 x m m p Clicker questiun Which planet W39 wou be easiest to find using his method7 A Highrmassplanettavtmrnstav a Luwrrnassplanettavtmrnstav c Highrmassplanetclusetustav D Luwrrnassplanet clusetu 51a Whamm5 s t E 65 e 22 mph Velacmchanve gt 5pm h m rm am am Denna m um my lvgwmma mg The Wobble Method the Dupplertechnique Speedpmin sue m mun a Then 1 P1 Canaan x a quotHot mixersquot l omith a 1 DB sularrnass KEI star MEI LY away Planet masle 14 MJ u m AU mm radius Evolution on ma Mllgnborlng Finals in a Plulas llhl m imam new Wobble method easiest to detect giant planets close to parent star h mm W mam m Butwhy do giant planets exist at less than 1 AU Spimlin inlnthes1av asa lean nal mamh Mn gas ms v hmhum w mmm Large ecuenlncmes due to planet iahet giavitalinnal him inns mama 5m m m livM vavS makes my may Wm H D 188753 Ab A Planet in a Triple Star System 12 e Wtield mith MOA 2007BLG192L The Smallest Exoplanet so far Discovered thruugh ravitatiuna EHSng DlYEEl measuve at mass 318 Earth masses Must be made ufruck El 62 AU frurn its star Elutstarhas EIan a DB sular masses The Sun We know the most about the sun 7 Howlong does the Su ve e What happehs to the sun when it dies Astronomical Horizons Public Talks Telescopes of he Future acilt al Win Abrams Planetarium Thursday at7 30pm First Light for the Spartan Infrared Camera E 0 Thursday16April Test 2 Results on wwwloncapamsu edu ead announcement on angel for instructions Overall grades On angel Reports tab Excused absences have Lifetime ofthe sun I Homework 5 at been tered 7 OHS Chapters 6 8 8lt 9 e on angel 7 Gravr t act aoga aznergy Jovian planets comets announcements asteroids formation of he Average e r m solar system extrasolar More than halfonhe F 539 Planets course gradei l e 4Hgt He Due 600am Wed 25 March Suh Viewed With x rays 35 forFiriai Exam 19th Century Energy Crisis Extract Energy from Gravity Luminosity of sun L4x1026Watt 39 laxmmwaquot Mass max 10 How long will the sun last if the energy is Ifmaterial fallsfmm Rum 0 9 m produced by burning coal CJrOz gtCO2 7 Life time mgtltEmL 7 l 2 82 r em mgh memmx e Llfe tlme mgtlt m n e 16Mllllo years 7 39 Kelvin s c au39on includes material falling not Em 9MJkg for burning coal juston face Got M 7 1500 years Kelvln i couldbethls old but later In 19 century age of earth was shown to be much Earth 15 much older than that larger I Inc2 Cnas Nu suluuunwnh phyaes er 19 th Ems39an39s newtnenryuuna 7 E7 m c1 7 En 7nasex s ens my F Cmnfgng a utue nass premees a 1ntn energy Cnrnpare k men energy v rnv2 wnn rn 7 Speeanrxrgnte 72nnnnnkns Arrnbxsstrnnnse mms at n 2 W5 chernreal reacuon coz7c 7 Em wmumnmnmn Onepartrn lUUblllmnuf rnass nappars and enangesr n energy Sun eontraets by 10 7 Em 1nnnuun Onepart mamllmnufmass napparsann enanges mm energy Nuclear fusion 1n anudmrm mn cmvmmga sm mm ammn nrtnerrasstn energyxspusslble HansE etne gured mlthenudmrphyscs nrnnw msnappens 4 H 7 He neutnnas 2e energy Whmh rs havm A bux ufhydrugmandabux er hehummeumnus andpuslmns rmde 39um the hydrngnnv A H a Pmducts He nentnnas andpnsmnns c Massrstnesanne E E 39D m ts E m eutnnns2e m may 1n a n nrtne nass tn margyxsp b1 41H 7 He neutnnns2e en 7 Ahydmgenmlclzx rnse 7 One hzhnm n Is 15 pmduced 41H waghs I7m rethan Hen 7 Panafthz mass hasbeencanvemd m e 7 Amanm afenexgyxs 571 Emmi Mnsmfmass ere hme 7 rngtltErnyL 7 m gtltE nmneumm 7 mnayr 7 In reamysnn Ises m7 affnel Llfeume 5 lEIEyI 4He2ev 4 Ltgmerby 07 Protonproton chain Watch aproton for an average of 10 Byr before reaetron m step 1 occurs p 211 e39u 7 Hanna repulsun Cuulnmb repulsmn CEILLlEImb tamer a msfastspeedaxhghtzmpenmmavexcamexepulsmn ed amphas very snau nass 1t Exits the sunvntnnut E 3 6 Step 2 211p aiHew Step 3 3He3Hea He 2p and u Parts of the Sun Core Enagyxsgmemted here Radratron zone ergyrnuvesby nun Conveetron zone Pnotospnere 39 Whalwesee cnrornospnere Corona Energy transfer Rad at on pnutuns ugnt travel a shm distance absurhed by aturns m Regal 39 Fhumns du amndumwalk at svmtually get ta eanveruunzane Fig m7 cuulerbubbles ran Nutrmpurtanz m Sm Use pnysres to eonstruet rnode1s Energy rs generated by nue1ear Interior of the sun rusron wnren depends on temperature and eornposruon e from eenter wnere rusron oeeurs to outsrde wnere rtradrates rnto spaee Gas gressure holds the mass of e s above tn Bart Seerrgmz Solar oscillations with GONG Observ the surface eaused by sound waves that go ernouono Sularsesrnulugy Srrnuartu anaryus ufEanh39s rntenur Wave patta39nrevals rntenur strueture Wave speed depends un cumpusmun at temperature and hem Contents of Solar System lt Explorin 9 th e Solar System We wild re ehmmtehsmex Tm lanets lt lnluvmatlun ehplusmh smc2197 s WWW W 3 dwarf plane s due m semigm m n tap Moons m mum u mhhehememem Asteroids u Wm l2 Teheeenm xn u emhthaemwmm Ruckv m ammmmmeeam 12 1 In Me e w hsne l5 5vlm 5ldumnce am7 0 c mels pends Wsedsuvgblllatnp m P Wmm lcy w emheemmv 8 wwwumvwxn Du w wwvermmwxv In em ammrDmbe wsznn 2 asehmmerpmbeannmnx Overview The n e planets 61 Clicker Question Which ofthe following is FALSE A 2 enhe other ahweys are NOT charactenstlcs enhe Sulav System a The planets all uvbltthe Sun quot1012 same dlYEdlun c The uvbns enhe planets Excludmg Plum all he lquot a thm plane 39 D The WHEY planets move suWEHn thew uvbltsthan the mute planets Ertur Emu Earth We mh Urinu uehhme Plum E Pluto s eyth l5 drastlcallytllted velatwe tuthe planets uvblts The Grand Tour of the Solar System A Look Back at the Solar System late 197039s courtesy of Isaac Newton39s work in the 166039s You too can gure um huw m an thls m1 use eh sa la s fawn TV The view back from Voyager 1 on its p way out ofthe Solar System Em yuu musHake mm Musalc er lmages taken 4n AU 4 when mllES account gravnatlunal mm the SW quotS e Uquot all amaene S e p anets 39439 m chi I l M The Expanding Universe I Individual galaxies do not get stretched I Light waves do get stretched 9 redshift 5 o a 3 m 1 151mm aoomma i eiiiim You T Al 100kback Planck Formation Galaxy NEW tlmE Elf H HE Ll Formation time corresponding Now Mam to redshi z DEW Bf Redshift 9 scale factor Rt at time light was emitted my K D9 K 3m K 3 K High density LOW density Cosmic Microwave Background Background Hotter L ii I Hydrogen ionized A I Universe opaque I Photons travel only short distances Prlmordlal Nucleosymhesls cosmic Mlcrowave i 4m can an i Bruinquot Yul I Absorbed reemitted by free electrons Tim Planck Formation Galaxy N T 3000 K time or H He ti Formation DW DiC 2Phi1g 13 7 billion 5 ago ln atiun Decoupling Universe 380000 yrs old of CME Hot Cool I Hydrogen becomes neutral p e39 9 H 1032 K 1 BB K 3WD KJ 3 K I Universe becomes transparent I Photons decouple from matter continue in Whatever H39gh dens39ty LOW dens39ty Cooler direction they were movmg Expansion of universe 9 redshift I Photons formed in thermal emitter with T N 3000 K I Redshi ing 9 lower energy per photon E hv hem So we see T 3 K thermal spectrum Discovered in 1965 i A Figl7 8 13 7 billion 1i ght years s a m D 391 FA I I l l wig Penzias Wilson and their radiotelescope The Sun Distance from Earth 93 million miles 39 1 5x108 km 8 light minutes Diameter 109 x Earth 39 1 4x106 km Mass 333000 x Earth 2x1033 g Luminosity amount of energy emitted per unit time 4x1026 watts 1015 times average power cons mption of US That s 10000000000000 0 times 0 Lots of energy per second The Composition of the Sun From spectroscopy of outer layers The Abundance of Elements In the Sun Percentage hf Number Firmnumb by Elmrant ol39Amms Hi Hydragen 9m Hmquot 73 Cuban DJJZ ELM Narnia DDUB El D9 Gunmen 005 3913 Mean 0J3 I G I 6 Written 13003 1M Sullivan 1004 U 39i39 Muir 0002 005 lmn 09133 0 H quot H J l I I quot malinmntl l 1 v A r i y I l 1 l l a 5111quot mud The Interior of the Sun 0 almost no observations of interior 0 Interior structure deduced from observing the outside Diameter 0 Mass 0 Luminosity Composition 39 Age What Powers the Sun Need to provide 0 4x1026 watts lt 2x1033 grams mass of Sun 0 gt 4 5 billion years age of Earth Energizer batteries A single Dcell 0 5 wattsbattery gt 8x1026 batteries required l39gbattery gt 1029 g total mass of batteries 0 room for 20000 times more batteries in reserve 0 but each battery lasts only 43 hours 43 hrs x 20000 98 years 69 What Powers the Sun Need to provide 0 4x1026 watts lt 2X1033 grams mass of Sun E o gt 4 5 billion years age of Earth How about H bombs 4 x 1H gt 4He neutrinos energy Hydrogen 1H Helium 4He Special Relativity pg 356 Einstein postulated 1905 The Principal of Relativity The laws of physics are the same in all inertial reference frames I The constancy of the speed of light Light travels through a vacuum at a speed c which is independent of the light source 1 I distance time velocity add up in funny ways Classical V vu 1170 mph v 100 mph Spe01al relat1v1ty V39 1 11V C2 For Slow speeds u70 mph v100 mph c 669600000 mph 1 uvc2 1 00000000000001 But all observers see light move at same speed V c u 1 uc v Vu0 99999999999999 C2 c Special Relativity Einstein postulated 1905 Mass to Energy 356 pg 4 x 1H gt 4He neutrinos energy 7 The Prlnc1pal of RelathIty The laws of phys1cs are the same in all inertial reference frames E 2 The constancy of the speed of light Light travels through a vacuum at a speed c Which is independent of the light source distance time velocity add up in funny ways Mass of4 x1H4 x 1 67353x1027 kg 6 69414x1027 kg 1 007 Mass of 4He 6 64648x1027 kg 6 64648x1027 kg Class1cal V vu Th u 70 mph V 100 mph e neutrinos have negligible mass gt S V u so 0 007 X mass ofH is converted to energy pec1al relat1v1ty V39 by c2 0 007 X 2 X 1033 g X 3 X 108 ms2 1045 Joules total available energy Total energy of a particle moving at constant velocity v 39 AVailable 316er LuminositY In X10453926 S 2 5 X 1018 S Classical E 12 mv2 1011 years Rest Energy SpeCIal relat1v1ty E ch 1thV2 is there even Actual number 1010 yrs because Sun Will evolve after central 10 ofits lVZcz Kinetic energy When V 0 mass is consumed and then Will die o Fig 10 5 F1ss1on vs Fus1on FUSIOn Iron Fe is the most stable nucleus 3 f Low speeds Fission Fusion Electrostatic repulsion wins 39 a Fig1041 Need high velocity J 9 bit gy high temperature a T at V2 mvz Heavy nucleus 6 g Uranium Light nuclei 6 g Hydrogen High speeds is propo ona to breaks up into lighter nuclei combine to form heavier o Protons overcome electrostatic repulsion Claus Get close enough together for attraction of strong nuclear force to win Clicker Question The sun produces its energy by Computing the structure of the sun nuclear speci cally through the reaction which Use equations expressmg the followmg converts 0007 of the initial mass of into d 1 I energy Gas A ssion 4 x 1H gt 4He neutrinos energy Hydrogen The sun Is a gas B fusion 1H gt 4 X 4He neutrinos energy Hydrogen The Sun is neither contracting nor expanding C fusion 4 x 1H gt 4He neutrinos energy Helium 39 Each point inside the Sun stays at a fixed D fusion 4 x 1H gt 4He neutrinos energy Hydrogen temperature E ssion 4He gt 4 x 1H neutrinos energy Hydrogen How energy generation rate depends on F The sun is actually powered by Energizer batteries density temperature composition How energy is carried outwards Models show Main sequence is where stars burn Fuel economy amp lifetimes i 4 H He A i d l gt E Spectral Surface Mass Lifetime o g yp Temp ltMegt yrs 2 t A v 05 40000 40 106 a 1 B0 28000 16 107 A0 10000 3 3 5x108 F0 7500 1 7 3x109 Mass fuel for H He burning Go 61000 1 1 9x109 I Luminosity rate at which fuel is used K0 5000 0 8 10 M0 3000 0 4 2x10 ML lifetime of star 0 star ML 20l000000 0 00002 time units M star ML 0 20 01 20 time units Predlcte pat s 0 stars on lagram Hwy MDxID39 m Luminaslly it in shell 1 5 Solar mass moo mum Su ace iempenavnre 00 see gs12121214 Star clusters are the testing ground 113 mmedin disk ofGalaxy ddl ed Globular Clusters N 150 in spherical distribution in out Galaxy All are very old Star clusters are snapshots of stellar evolution 1w All stars in a given cluster formed at same time But with a wide range in masses Main sequence lurnq 39 stars just nishing main sequence evolution Diagram 21 young cluster Luminosity Lm Smfaee temperature clusters T em Me yrs T thousands deg gt Summary Nuclear burnlng 1n stars What Stars do 39onli I Gravity 9 Star always to contract become more dense f quot I Nuclear burning interrupts this EVOIUthI through 111101551quot I High temperature 9 high pressure urni I Pressure halts gmvitational contraction Mmmal gt 2MG Nuclear burning all the y I Mmaul lt 2MG Nuclear burning shuts E off er He burning Possible endin 1 a white dwarf Suf mently h1gh dens1ty 9 Electron degeneracy g I Pauli exclusion principle 9 cannot have two electrons in same place with exactly same energy For mass lt 1394M0 I Pressure from electron uquot rr Fla 1271 degeneracy can support star u r 39 1 M W f nl Wittfair W W 39 39 1 L it w d A i m 2 1 u H 39 we mm now m Normal gas room for electrons Degenerate gas almost all I A crystallike lattice ofnuclei to squeeze together energy levels lled I Electrons conduct heat outwards to surface I Surface is steadilycooling thermal emitter o P f d t 1 tr d d l ressilre mm egenera e e ec OHS epen S on y on I Whitedwarfs evolve down and to right on HR diagram density NOT on temperature I Can have high pressure without nuclear burning Possible ending 2 a neutron star 5 0f mum Stars T Paiod If degenerate electron pressure cannot support the star 3 P t l l l Jt l l l s e39 p9 n neutrinos 3 J Jl A LA J g Time I Still denser state of matter than electron degeneracy 39 E gtisr any found repea ng radio I Sun 1000000 km diameter I White dwarf 10000 km N same diameter as Earth I Neutron star 20 km I Rapidly spinning neutron star emits light in beams I Dozens now known I Rilses repeat with 0 001 to 10 sec 39 I Many also detected in visible I Degenerate pressure of neutrons can support stars up to 3M light 0 033 sec pulsar is next to a star of constant brightness The Future Sun Homework 5 is due 630am on Friday 23 March Public viewing sessions at MSU campus observatory Fri amp Sat 911pm if it is not cloudy Mar 23 amp 24 Apr 20 amp 21 May18amp 19 Giants are dying stars white dwarfs are dead stars Why does the sun die What will the sun become when it dies Giants are dying stars white dwarfs are dead stars Evidence on giants from star clusters Compare members ofa population All stars in a cluster are born at once Formation time is the collapse time of the cluster which is very short lam a G star like the sun I have 100000 fraternal twins some weighing 30 times my mass some 110 of my mass M80 Pleiades tar clster Pleiades 30000 10000 6000 surface temperature Kelvin Not all fainter stars were observed For all star clusters main sequence extends to cooler stars beyon observations In what ways are HR diagrams of llx Perseus Pleiades Hyades amp NGC188 different Q Which is false a Perseus has hotter stars than Pleiades Most stars are one h T X Perse the main sequence Perseus has small range of luminosity Some clusters have giants luminosity solar units 039 O 0 30000 10000 6000 surface temperature Kelvin Stars with hih mass live a short life 104 O N Luminosity H o 0 25000 10000 5000 3000 Temperature HR Diagrams of star clusters Q2 There are no A stars in M80 because a they never formed b they died and disappeared c all stars became redder as they get older d they are too faint to see HR Diagrams of st Q3 The hottest dwarfs I in Pleiades are A stars Y The hottest dwarfs in M15 are F stars Pleiades is than M15 Luminosity a older b younger LIfe of the sun T a 1 J Heat source moves closer to quot2395quotquot y concernotggnon surface39 I Layers below surface swell up I J Tempemlm Star becomes larger J an Surface becomes cooler Red giant Present sun K HHe burning core Inert H Temperature Luminosity Radius Phc msphere uin Sum Wuhana Concenlration Life of the sun Hydrogen Temperature Heat source moves closer to surface Layers below surface swell up Star becomes larger Surface becomes cooler Red giant 5 Byr from now Inert He core HHe hurtling shell Inert H Luminosity Life of the sun Hydrogen Concenlmllon K r I V f Temperalure MIMI b Radius 39 photosphere mam Vmiuawa Temperature Heat source moves closer to surface Layers below surface swell up Star becomes larger Surface becomes cooler Red giant Few 100 Myr later Inert He core HHe hurtling shell Inert H Luminosity Life of the sun Heat source moves closer to surface Layers below surface swell up Star becomes larger Hydrogen Concentration Temperature Surface becomes cooler Red giant Later radius b Inert He core Radius photosphere Hquot In 9H6 bummg 39 39 shell 41394quot I 39 Inert H Temperature After helium is used up Reaction Min Temp 41H 9 4He 3 4He 9110 12C 4He 9 Ne 9 O 9 Si 9Fe 107 K 2X108 8X108 15X109 2X109 3X109 S Contraction heats center Helium starts to burn Luminosity election or 10000 E I t b i E helium p ane ary 1e u a 1 I he future 000 5 E thermal pulses e 39 transition to 100 5 whne dwarf S 39 conlraction 0 E D39 p mosmr leaves main 5 uence 1 Earth s orblt Notice changes in scale ejec on 0f planelary mbu a AILA 122 123 123650 123655 he ium lash conlraction of proloslar eaves main seq uence Radius transmon 0 whiiedwad LJ LL I J L I I L4LILLA11 0 5 10121 122 123 123650 1273655 Cat s Eye Harrington amp Borkowski UMd amp NASA Helix nebula Gas amp dust ejected by star in the middle Ejection occurred several times Wind blows gas into previous ejecta Colors Blue 0 Red H amp N NASA NOAO ESA Hubble Helix Nebula Team M Meixner STScI and TA Rector NRAO NGC 6826 Wind from hot star blows on material expelled by pulses Balick U Wash et al amp NASA Age amp Comets February 25 Age of solar system 39 TeSt 2 determined with Mon Feb 28 meteorites Covers Comets 6 questions from 0 Missouri Club Test 1 Added to score of Test 1 Telescopes Solar system Format similar to Test 1 Homework 3 closes 3am Mon MCtCOI39S often pieces of comets 0 Small particles burning up in Earth s atmosphere 0 Typical meteor 1 gram size of a pea Bright reballs golfball sized particle Bowling balls would make it to Earth s surface Meteorites always pieces of asteroids The particles that make it to the Earth s surface Allende meteorite Mexico 2 tons of fragments recovered after airburst Meteor showers 0 Result of Earth passing through trail of debris from an old comet 0 Some trails spread out ove 0 Others are clumped up See Fig 9 9 Radiant The direction from which the meteors appear to come Determined by combination of motion of meteors and motion of Earth nc items and derived items copyright Gilt2000 by Harcourt inc Meteor showers Direction of Earth usually best V1ewed just before dawn This is when Viewer is on side of Earth nearest direction of Earth s D1rect10n of motlon meteors Earth s motion causes higher rate of impacts on this side we e overtaking af c Shower Date Comet Comet Period Eta Aquarid May 5 Halley 76 yrs Perseid Aug 12 SwiftTuttle r105 Orionid Oct 21 Halley r 76 Leonid Nov 17 TempeITuttle 33 Cmyrghl 209 Pontoon Emmm mmmng as AMvson Waste4 enema 2004 Pearson Emcwm cub ishng as Adamoquot www large object Stony right Carbonrich right Formed in outer asteroid belt Age of rocks K40 Ar40 e 125 Billion years Radioactive decay pg 159 unstable atomic nucleus decays into stable nucleus different element 39 Examples 0 Q A meteorite is found 0 Q The nuclear chemist is Uranium238 9 Lead206 8 X Helium4 4 5Billion years with K40 and A140 in the concerned about heating Potassium40 9 Argon40 et 1 25 Billion years ratio 21 Its age is during its passage through 19quot 21 18quot 22 125 Byrs the earth s atmosphere 100 Hallefe Potassium Argmw a Older than The surface of the Time for 12 of radioactive b Close to meteonte would appear be nuclei to decay a 075 k c Younger than than the center if o Minerals form with Fig 628 heating is significant radioactive elements 2 0 50 ha39f39me a Younger 9 daughter nuclei that b older shouldn t be in pure mineral 5 025 2 ha39l39l39ves Ratio of daughterparent nuclei 0125 3 ha39HiVQS 9 age since mineral formed 1 I I I 0 l 2 3 I 4 5 125 25 375 time since rock formed billions of vears Isotopes in primitive meteorites date of formation of solar system Primitive meteorites have very narrow range of ages 448456 billion yrs Average 454 billion yrs Primitive meteorites contain Xenon129 Iodine129 is made in supernovae exploding stars Iodine129 Xenon129 17 Million years Xenon129 is a gas even at low temperatures gtMeteorite form a few tens of millions of years after a supernova gtA supernova triggered collapse of cloud that became solar system Comets 92 Small icy nucleus Dirty snowball model mostly water ice 39 other ices mixed with silicate grains and dust Outer layers of nucleus vaporize when comet approaches sun Little geysers and eruptions observed Comet s head Coma often as large as Jupiter up to 250000 km diameter Primarily H20 gas 39 few percent C0 C02 and hydrocarbons Huge hydrogen clouds around head can get bigger than sun This fading super comet continues to be visible in small telescopes aJrnost 5 years a er it was discovered Despite now being out beyond the orbit of Saturn the comet c 39 es t dis a e im 12quot 13916 newtonian telescope at prime focus Taken by Maurice Clark HaleBopp 1997 Cornet HaleBopp February 7 2000 o D age is a combination of 3 3minute exposures using a 416xt CCD and a april 9 199 39F Comet Hale Enpp 1995 01 Comet s orbit dustta ionta up to 10 million km long smokesized dust particles H I driven off nucleus by escaping gases 5 Sggg agpeennm km pushed outwards by Sun s radiation competing force of Sun s gravity curve in tail Up to 100 s of millions km long small charged particles pushed out by charged particles from Sun solar wind 45 minute 4200 yrs since last appearance 0 2400 yrs to next passage 0 perihelion 0914 au inclined 90 to plane of solar system HaleBopp s orbit Comet HaleBopp Nov 15 1997 Come HaloEon Dale Ireland 1997 mdrdalmcam Halley s Comet first observed 239 BC 76 year average period most recent visit 1986 fizzled out last time around Halley s nucleus Nucleus is 10gtlt15 km 6x10 mi Nucleus is irregular in shape Nucleus is jet black Evaporation is con ned to small regions VALLEY CHAIN OF HILLS BRIGHT SOURCE CRATER Picture taken by Giotto MOUNTAIN Sun CENTRAL DEPRESSION REGION BRIGHT PATCH ROTATION AXIS ORIENTATION TERMINATOR Oort Cloud amp Kuiper Belt 0 No comets have orbits coming from interstellar space 0 Strong tendency for aphelia at 50000 AU 0 No preferential direction from Which comets come Best current model The Oort Comet Cloud 0 1011 1012 comets in loosely bound solar orbits at 50000AU Ejected by Jupiter into random directions 0 Gravitational perturbations occasionally de ect one in 0 Guesstimate 1 trillion 1012 comets total X 103910 earthmassescomet 102 earth masses total HSdeiheia h Iheh hstosphere 75 memmmclwemeaswed usngsesmcaaes CNS 39zveMensmzsk 394mlhskuntemeans n39 W Wmmmmemznlnenls W I e 21uxygenmosry02 I anHe HIQUHNQOCOQBIC 39semszm 395sz g z 39Ozone03scrrmoreg w w 39hncksun39surmvmer I L m 39J Meme 39mnskeelz nut w WHEN I J39 Heamemems sankmcenm 39 MeEanhwas nren Wmalzn SpacesMe I t 5 W5 3 U Prospecting on the Moon Apollo s Accomplishments PR Beat Soviets to Moon Example Selsmulugy ur Earth s interiur Science Le behind seismographs and other instruments Moonquakes show internal structure of Moon No life on Moon Brought back 400 kg of Lunar rocks Composition Age Composition Highlands Low densltv rocky slag formed on top of molten Moon Maria Huge lava ows from volcanoes Basalts 7 Similar to volcarllc rock on Earth 39 but no Water fewervolatlle easllv melted elements Much less iron Age dating from radioactive rocks Radioactive decay Examples Urarllurn7238 Lead7206 8 X Hellumrlt Potasslumezlo Argorlezlo e 119 21nl imp 22m 00 HamTe PamMi AD Martin nuclel t0 dec Minerals form with radioactive elements 39 daughter nuclel that shouldn t be in pure mineral will Ratlo of daughterparent l n nuclei age Since mineral l Tlrne for iZ of radloactlve we 7 5V Fig 625 imam ul minim i l r i formed a 7 l 3 i4 5 i s a 375 Age dating from radioactive rocks Clicker Question You start out with 4000 Potassium40 atoms How many are left after 125 billion years A 4000 m B 3000 W c 2000 w39r D 1000 r Figs251 E 500 l L i J i s quot Jr 3 5 Age dating from radioactive rocks Clicker Question You start out with 4000 Potassium40 atoms How many are left after 25 billion years A 4000 m B 3000 mm c 2000 g M D 1000 r Figs251 E 500 E E Plumlurk l i i l i i 0 39i 9 I 3 1 I 5 January 19 Galileo 1610 looks at the sky with a telescope First homework Outline Galileo disproves Ptolemy s Discovered Open lessons folder earthcentered model of the Milky Way myriads Of stars Start on Fri let solar system left over from 0 Phases Of Venus Must finish by 3300 am Wed 15th con rmed heliocentric model 26th I Tyco Brahe measures the SunSpOtS BeSIdes astronomy questlons p0s1t1ons of the planets Craters maria on Moon Rings of Saturn 4 Moons orbiting Jupiter you will register your clicker Kepler nds Laws describing number on thls aSSIgnment motion of the planets Clicker questions now count in your grade The lowest 10 of your scores on clicker questions are 1 EIMSS mm dropped Galileo s telescopes 1 in diameter X 243 0 long Galileo saw the phases of Venus Galileo saw 4 moons orbiting Jupiter aux at af g m ma quot ew Cr zwfd in Hercuru L 39 V I gill A a 4 germ unk9M quot f diu Ly39nm 2ka g V I hrv r f39i i i 34quot 1 9 t gFHaSg j ga ggZ d g zu nfa39 Ail 39 mayM VF39B I a 4 m l39a thl 5 Z zW mw aq g quot jad a 194 lama a J 39 MIMIa ruin 2129 34 MA417 HIS 5143 Image through modern telescope W showing 2 of Galileo s satellites Ptolem 399quot Co emicus 14 2 5 a y p gm law a 39 and the1r shadows 6 a 5 quot Jw r Gallo g hgf39w bl 1 quot39 t Venus 939 quotH 4931 a rhilft hlet 32 H zu m MWww 19 enter of 7145437quot m39 4 ii ai epicycle v31 7 i g 1 4 my a g maaTU 4 Km 95 M ff g rm fmb n ja gm mm sittil WWQMQMM Q lquot m Blitz 1 H The old boy s observing notes Earth What Galileo Saw The milky way jillions of stars 1 Questions on reading Chapter 3 When Kepler was a college student the most accurate description of the motion of planets uses the terms a b 0 Velocity position amp acceleration Circular orbits Elliptical orbits 2 Same question 3 Today the most accurate description of the motion of planets uses the terms a b 0 Velocity position amp acceleration Circular orbits Elliptical orbits Craters maria on moon More Galileo discoveries Galileo s sketch 1616 Rings of Saturn Sunspots QVADRANS MVRALIS SIVE TIGHONICVS Great quadrant 1582 Tycho Brahe s Observatlons On Uraniborg Tycho measured positions of the planets for 20 years Highly accurate amp reliable Accuracy limited by human eye not by instruments Superseded only With telescopes Tyco measured amp compensated for instrument exure the biggest error Revolving steel 2 quadrant 2 m W45 umuf Brass azimuthal quadrant 65 cm radius ca 1576 Johannes Kepler analyzes Tycho s data Kepler was Tycho s assistant 0 20 yrs data on planetary motions Tycho tried to t data with Ptolemylike model Kepler analyzed the data 0 Found 3d orbits from 2d positions in the sky Concentrated on orbit of Mars 0 Had to subtract off Earth s imperfectly known orbit Discovered 3 laws which describe the motions of all the planets Brahe 1546 1601 Kepler 1571 1630 Their meeting at Benatek in Czechoslovakia on 4 February 1600 Tycho de Brahe and Johannes Keplerus co founders of a new universe met face to face silver nose to scabby cheek Tycho was fiftythree Kepler twentynine Tycho was an aristocrat Kepler a plebian 7 Koestler The Sleepwalkers p302 Kepler s 3 Laws Pg 64 focus equal areas of space in equal amounts of time p2 a3 0 P period of orbit in years 0 a semimaj or axis of orbit in au Sun at one focus Semimaj or axis Major axis Min r axis Each planet moves around orbit in ellipse with sun at one The straight line joining the planet and the sun sweeps out Semimaj or axis Earth s orbit is nearly circular Kepler s first law Each planet moves around orbit in an ellipse with the sun at one focus 0 Ellipse is a conic section 0 Along with circle hyperbola This is an unexpected result 0 Why an ellipse 0 Why is sun at focus rather than at center Kepler s second law The line joining the planet and the sun sweeps out equal areas of space in equal amounts of time planet moves more slowly when it is far from sun more rapidly when close to sun 0 see the Formation of Helium in the BB A fossil is a remnant or trace of the past Amount of helium is a fossil from the Big Bang Mass HeMass H1 3 neutronsprotonsl 7 Three snapshots 39 3min 4717 Fossil from Burgess hale Now np17 Please rateyour class at 7 rateyourdassmsuedu 7 Closes on M 8quot Open house at MSU Telescope 39 Nebula the moon amp other wonders through the 24 7 Friday and Saturday May 1 and 2 from 930pm 11pm weather permittjn 7 observatory is on Farm Lane amp Forest Rd south of campus Homework 7 o m on Tues April 28 just before Missouri Club Missouri Show Me Club 7 Room 1415 today 700800pm 7 One 8V2 X11 cheat sheet 1 At the present time np1 7 Where are all of those neutrons A in 4He helium with 2p amp 2n B in 150 oxygen with 8p amp 8n C in 12C carbon with 6p amp 6n Neutronsprotons when U was 0001s old 39 00015 7 Temperature 400 40 MeV is much r lt gt BK 39 greater than cost to be a neutron r np 11 Later at 0015 the temperature of the U is 7 A Warmer B cooler N C same At later times 0015 np i5 7 A higher B lower C Production of deuterium Production of deuterium hydrogen with one neutron e n a 2H en Ifthe unlvase ls too hot radlatlon has so much magy Lhat deutalum ls broken ap art Once deuterium forms and becomes stable helium forms quickly and all ofthe neutrons are locked in 4He 0001s e Tenperature 400 BK 7 E240 MeV is much greater than cost to be a neutron e n p 1 1 e Deuterium is easlly broken apart if deuterium amp 4He could form at 0001 s how much helium and en would form from 16 nucleons Mass 4He and mass H are hydro A 0 B 83nd8 C l6and0 D 43ndlZ Production of deuterium Production of deuterium hydrogen with one neutron n p a 7H energy Ifth unlvase ls too hot radlatlon has so much magy Lhat deutalum ls broken ap Once deuterium forms and beco and all ofthe neutrons are locke If deuterium amp 4He could form at 0001s how much hydrogen and 0 s He mdmassH are mes stable helium forms quickly d in 4He 1 helium wouldme fr m 16 nucleons Mas A 0 and 16 B 8 and 8 c 16 and 0 D 4 an d 12 rium amp 4He form later does i helium forms 2 Lfdeute A less B more c same amount of Neutronsprotons when U was 3min old 7 Temperature 1 BK r E0 war is much less than costtb be a neutron As universe cools np drops because the cost of being a neutron is m e and more expensive 9 CD 7 n p l 7 Production of deuterium hydrogen with one neutron e n p a 2H are FEY At 3min deuterium becomes stable Neutrons get locked up in 4He How much helium and hydrogen vvouldform from 16 nucleons Mass 4He and mass H are A Dand16 B 83nd8 c lsando D dlz Neutronsprotons when U was 3min old As universe cools np drops because the cost ofbeing aneutron is more and more expensive 9 D 39 3 mln At 3min deuterium becomes stable Neutrons get locked up in 4He 7 Temperature 1 BK 150 lMeV ls much less than lt10st be a neutron How much hydrogen and helium wouldme from 16 nucleons Mass He and mass H are r n p l 7 production of deuterium hydrogen with one neutron n H 7H me tgt 4 and 12 39 25 ofmassisinAHe and750fmassisinH Neutronsprotons at the present time Now l3Byr Temperature 27K E iny np 7 17 Production of deuterium hydrogen with n n p gt 2H energy At 3min deuterium becomes stable Neutrons get locked up in 4H6 25 ofmass is in 4He and 75 ofmass is in H Neutrons are safely in helium Amount of 4He has increased slightly because A helium is made in stars B neutrons are still changing into protons Collecting the Fossil 4He 7Li 2H amp 3He are made in BB Lots of 4He Trace amounts of 7Li 2H amp 3He Diagnostics Measure abundances with spectra of primordial objects First stars in our galaxy made before much of the material had been processed through stars Dwarf galaxies where material is processed through stars very slowly mumH Waveiegnlh WWSEI Flux Deuterium 2H has same spectra as hydrogen H but slightly shifted Abundance of 2H Strength of 2H spectral line compared with lH line Relative Velocity kms 0mm 21 ai 2mm Am 552718 QED Moons amp Rings February 18 TWO loaner Clickers Galilean Moons of Jupiter Borrow them for the class 39 Rings 0fthe JOVian planets Does not count against the two t1mes you may turn 1n paper answers Homework closes at 3am on Tues Finish before you sleep Monday night Moons of Jupiter Age of Surface 1 Which moon has the oldest surface Do not look in your book Examine the pictures amp deduce the answer Hint Compare the appearance of surfaces of earth amp moon Which moon the olt surac Ert amp oon ad similar number of meteors Craters on earth have been erased by weathering amp tectonics Answer Callisto D Tidal Heating of Jupiter s Galilean Moons Xx x XIX larger tidal bulges when closer to 7 Jupiter Jupiter small tidal bulges Fig 815 R Mf Diameter Relative Density Reflectivity km Mass glcm 3 Moon 3476 10 33 Callisto 4820 15 18 Ganymede 5270 20 19 Europa 3130 07 30 lo 3640 12 35 Callisto Orbital period 17 days Tidal locking with Jupiter Surface temperature l4OO C appears to be mostly ice l 8 X density of water 0 Many impact craters Not well differentiated 12 20 40 70 60 Callisto Close Galileo ybys 9 gravitational eld 9 no dense core Geologically dead for 4 billion yrs Callisto Fewer impact craters than Callisto 9 geologically active Differentiated Rock metal core Magnetic eld present Mantle crust made of ice Volcanic ows but water rather than lava Ridges valleys due to compression of crust Ganymede Largest satellite in Solar System Ganymede Europa Not made of ice Density similar to Moon Tidal forces keep it geologically active Covered by layer of water ice Appears to be pack ice on top of an ocean Water must be warmed by heat from Europa s interior the occasional impact 0 uro rater a s surface 1 l5 FE 1quot ane s Ice ow cutting across ridge lo 0 Closest to Jupiter of Galilean Satellites Strongest tidal forces 0 Active volcanoes hot silicate lava similar to Earth l o 7 quot Loki Patera Images of same reglon 5 months apart Thought to be a liquid sulphur lake with a Haemus Mons solid sulpher raft a volcanic cone Schematic of V j Jupiter s Outer Satellites The Innermost Moons of Juplter University of Hawai i Institute for ustrcrrmcm39tyF 44 New satellite orbits are shown in red Retrograde sate39l39tes 39 Metis Adrastea Amalthea Thebe 2 What holds a yardstick together 5 r a Gravity P QER 3 I 2 v b Atomic bonds between the atoms rogra e 39 satellitesjti 3 What holds Io amp Metis together a Gravity for both b Bonds for both c Gravity for 10 bonds for Metis d Gravity for Metis bonds for IoAmalthea 5 million km i I amp10 Roche limit The Innermost Moons of Jupiter For a moon in orbit around a planet P2 a3 different parts of extended b have different orbital periods 0 So body tends to be torn apart More import 0 But selfgravity tends to hold it together Moe 1 lMetiS Adrastea Amalthea Thebe I 10 far out Size km 40 20 270x166X150 116 3630 Roche s limit is where these two opposing e Mass kg 10 2X10 7X10 1017 9W are balanced Orbit radius 128000 129000 181000 222000 422000 39 km R 25 3 R Roche planet p moon planet Inside Jupiteras where p density kgm3 and Rplanet radius of planet Roche limit If density of planet amp moon are the same then Amalthea RRoche Rplanet amp10 Saturn s rings All 4 126 top amp bottom views J ov1an planets 70000 km wide have rings only 100m thick l I gt lgt Uranus Jupiter s ring see Fig829 4 Imaged by Voyager amp Galileo Bottom View showing the light that is not re ected by the rings Neptune Colorenhanced top View Fig 8 29 showing spokes of unknown origin 4 Why can t the material in the rings collect to form moons a There is not enough material b The rings are too thin c The rings are inside the Roche limit d The rings are not made of sticky material Why do the rings still exist jovian planet Tidal forces near the planet prevent gma lt tumonlets are occasionally moonlala rum actuating irntn larger rrlcmnrsi disrupted by impacts Ring material continually ground down to dust must be constantly replenished from I moonlets Clngaing small impacts blast mt dust and debris to farm the rings Roche s limit and the Rings Large objects cannot form in this region or get broken up even if they do form Juphe l Saturn if Ii III l l i A C B A F Uranus l a I n n n n g l Neptune o a a o Planet Tidal su Haw stabillly iimil Roche limit Strong winds differential rotation w 81 mquot m K39 on 59 so i i m 4 w 7 2quot m l 30 l F8 m r g m t Ir n quotC5 5 La 5 my 55 23 y 4 u quot3 1 439 r 0 ml 70 w t k I eatquot r V 7 a 100 0 100 200 3 0 100 0 100 200 300 400 500 Rotation velocity kmsec Different than Earth 0 Fast spin 0 Absence of solid surface underneath Our Milky Way Galaxy What is our Milky Way Galaxy made of Stars and gas orbit the galaxy Dark unseen matter makes up most ofthe mass Test 3 New date Observatory open house Thurs 9 April Fri ampSat 9001100pm One cheat sheet MSU Observatory south of Study guide amp practice test A9 PaVi39iOquot Linkon syllabus Weather permitting Add Jovian planets Class of 326 history of w and highmass stars is included Today39s class is not inc uded Missouri Club Show me Tonight 715815pm m 1420 Disk 0 Stars gas and dust 0 Young amp old stars 0 Motion is circular Bulge 0 Stars are dense 0 Motion is ellipticalin all directions 0 Halo 0 Stars are sparse dark matter 0 No young stars Spherical in shape Motion is elliptical in all directions Globular clusters Parts of the Milky Way Sun s location g glazulmclusms splral arms bulge halo 1000 lightyears globular 39 cl usters lt 1ouono lightyears You are the sun The students in the room are 0 stars The center of the Milky Way is drawn on the board Where is the disk a All aron including up amp own FY Above the ceiling Toward the front of the room 0 P Within a few meters of the oor N Where is the halo Where is the dust amp gas Where do you see the most stars 55 Parts of the Milky Way l r globular cluslm smral arms V39 Disk stars move in a circle around the center of the Milky Way Orbits dip above and below the plane of the disk Halo and bulge stars move in long skinny orbits in all directions Why do some stars mo in a circle and others move in an skinny orbi Why does the earth mo in a circle today Planets are heavenly objects Orbits of stars halo star orbits green bulge starorbits red 33 57 It moved in a circle d k b is starcv 5 yesterday yellow Fquot gt1 Why do some stars move in a circle and others move in an skinny orbit Why does the earth move in a circle today a Planets are heavenly objec b It moved in a circle yesten Why does the earth move iI circle a The material from Which earth formed moved in a circle Orbit determined at star s birth Orbits of stars halo star oran green bulge star orbits red Gas that formed disk stars V orbiting MW in a circle Iar DIbllS w 1 disk 5 yello galaxy that got caught by N Earth 6Mrn in radius 1501ight sec Solar system Earth is 1 AU from sun 163000 light year 9 lightmin 20000x Nearest star Distance to Proxima Centauri is 4 1y 200000x Milky Way galaxy Distance to center is 30 kly 10000x Nearest big galaxy Distance to Andromeda is 2 Mly 100x Farthest galaxy seen Distance is 10 Bly 5000x Galaxies ll spae around us r 397 a Loneliest object Earth 6Mrn in radius 150 lightsec Solar system Earth is 1 AU from sun 163000 lightyear 500 ls 20000x Nearest star Distance to Proxima Centauri is 4 1y 200000x Milky Way galaxy Distance to center is 30 kly 10000x Nearest big galaxy Distance to Andromeda is 2 Mly 100x Farthest galaxy seen Distance is 10Bly 5000x 51057 Planets are 10000 earth radii away from earth Analogy you are 10000 persons 12mi away from the next person 1 Which is the loneliest kind of object Earth to next planet Solar system to next star Starstar to center of MW MW to next galaxy Loneliest object Earth 6Mm in radius 150 lightsec Solar system Earth is 1 AU from sun l63000 lightyear 500 ls 20000X Nearest star Distance to Proxima Centauri is 4 1y 200000x Milky Way galaxy Distance to center is 30 kly 10000X Nearest big galaxy Distance to Andromeda is 2 Mly 100x Farthest galaxy seen Distance is 10 Bly 5000x Planets are 10000 earthradii away from earth Analogy you are 10000 persons lZmi away from the next person Which is the loneliest kind of object Earth to next planet 1 2mi Solar system to next star 250mi Starstar to center of MW 12mi MW to next galaxy 200m Weighing 21 Galaxy NI What is the mass of a galaxy 7 Answer before 1974 Mass is that of stars amp gas 7 Actual answer Most mass is not that of st amp gas Mostmass is dark Dark mass is less concentrated How to measur b1974 Mass here a 1974 Most mass here Fn39tz Zwicky 18981974 Vera Rubin 1928 www astrusurf urglumbry Wp library ucla Edu HmagESlwmky pg imagesmum Mpg NGC 3672 w w s ncaun Edu frElGcatjtmCatalugCJpEgn3672 jug Light Thermal Radiation What can we learn by analyzing light Example of globular cluster Thermal radiation Radiation of warm bodies See if your name was registered Click Register your clicker if you have not already Email me your number HlTT records your answers but I want to give credit to a person not to a clicker number Homework 3 is ready on angel Due at 600am on Tues 30 First Test is Thurs Feb 1St About 30 multiple choice esions Some require working with models such as phases of Venus amp zodiac Fig 212 Click on Study Guide amp 2005 Test on ylla us Class of 25 h is last class on test How to study Identify Big Ideas Practice models amp examples Do 2005 test Go over homework amp clicker questions Missouri Show Mequot Club Mon 29 700800pm 1415 BPS Light Almost all we know about astronomy comes from analyzing light Example globular clusters Around 1915 Harlow Shapley figured out the distances to the Milky Way s globular clusters What do you notice about the light of the globular cluster M10 Globular Cluster M10 Light Almost all we about astronomy comes from analyzing light What do you notice about the light of the globular cluster M10 Color Red stars are brighter than blue stars 2 Red stars are giants about the size of the earth s orbit Spectra show M10 has much less oxygen and ot er elements heavier than Li than 0 is very old one of the rst systems to have formed Spectra shows the speed of Globular CHIS M10 M10 is very fast compared to that of stars near the sun 2 orbits of globular clusters are long amp thin whereas sun s is almost circular Wavelength Frequency Wavelength 7 distance between successive crests v V W m meter A A gt 6 nm nanometer 10399m A angstrom 1010m Wave moves at speed of light c Frequency is rate at which crests Cyclessecond Hertz Light is quantized A photon is a quantum the smallest amount of light v v MW A photon carries energy A A E h f h ck h is Planck s 97 constant A photon can do an amount of work E Give an electron its energy Make an electron move faster A photon carries momentum p h f c h 7x A photon can give a push Push an electron against pull of gravity Thermal radiation Blackbody Radiation also emits g If not it would get hotter and hotter Could get energy for ee Any objectlth t absorbs light I A perfect absorber perfectly black emits a characteristic spectrum of light Called thermal or blackbody radiation Intensity depends only on Temperature Area A nonperfect absorber grey body with emissivity s absorbs a fraction s and reflects a fraction 1s lntensity is s that of thermal A perfect absorber perfectly black emits a characteristic spectrum of light al ed thermal or blackbody radiation Intensity depends only on Temperature Area A nonperfect absorber grey body with emissivity s absorbs a fraction 8 and reflec a fraction 18 Intensity is ethat ofthermal ra iation Thermal infrared Wavelength is 8000 12000 nm An object with a temperature of 00K emits most of its lig tin the thermal in rare Does infrared light show the same thing as visible light Infrared camera Seeing with infrared eyes Q1 As viewed with an infrared is my earlobe darkerthan my lips A My earlobe has less area than B My earlobe has less emissivity C My earlobe is cooler Q2 The emissivity of a mirror is Q3 As viewed with an infrared camera the window is dar because A It is cold and emissivity is 1 B There is little infrared radiation in sunlig It is cold and emissivity is 0 Emissivity is 0 00 Thermal Radiation Heat up hot plate or a star It glows more brightly as it gets hotter It changes color as it gets hotter Temperatu e Color K C F Completely cold 0 273 459 Does not emit light Body temperature 310 37 99 Infrared Blowtorch 4000 3727 6740 Redhot Blast furnace 6000 5727 10340 Whitehot Hotter still 7500 7227 13040 Bluehot HertzsprungRussell HR Diagram Hertzsprung Russell D1agram March 16 Stars AAldebaran BBarnard s Star C Try new format for some Effng giggiz ndquot Readmg Hertzsprung39 Capella DRigel clicker questions Main sequence is a mass sequence 1 What do you need to know about stars to M Lifetime of star S answer the next 4 questions Pick one 104 39 OTC llke test unSUOIlS Do you understand HR Diagram of star correct ans Do you understand dimer a Hotplate model of star b Model of the solar interior c How to read HR Diagram d Spectrum of black body e Energy generation in the sun Fewer leading questions Public viewing sessions at MSU campus observatory Luminosity Lsun 2 Which is the hottest star 39 Fri amp Sat 911pm If It IS 3 Which is the smallest star Cummimdmm not cloudy 4 Which is the biggest star 104 m 39 39 Mar 18 amp 19 5 If stars AD replaced the sun would quotms Apr 15 amp 16 people be able to live in Michigan a YNNN 39May13amp14 NYNN 0 B A F G K M 241nch telescope 1n don 3 m 25000 1008013wmmzzsoo 3000 small telescopes outside e W Temperature K see Fig 1110 k11th 9 HertzsprungRussell HR D1agram Takmg a star 5 temperature Stars AAldebaran BBarnard s Star TWO Ways Fig 5 10 15000 mar CCapella Dngel g 106 the Sun 5800 K What do you need to know about stars 0 m 139 m n to answer the next 4 questions Pick 104 CO pa a Cu t E13 106 S DOO K Star one correct ans Of in tWO E 104 a Hotplate model of star LR2T4 quotg g f b Model of the solar interior X 3 COIOIS g 102 c How to read HR Diagram V 5 d Spectrum of black body Hottergtblue1 1 BlaCkbOdY curve m Qi 1001 152 153 154 155 e Energy generation in the sun X 8 W 1 h Which is the hottest star eCtrOSCOpy agelfllfrtgy Which is the smallest star g Gammaquot mm 3 Which is the biggest star 104 mar Sodium If stars AD replaced the sun would mm Hydrogen people be able to live in Michigan a WW I o B A F G K M caldum 2 EN n HYNI 25 000 10 Stiiledral c1200 3000 Mercury 1 NNNE G Temperature K Neon Wavelength see Fig 1110 Annie Jump Cannon Classify stars by their spectra lllllllillillll leGliilllllilHEll E 39 AJC in R r A W W A like 0 a 111 we Prof Pickering s i M w i 7 quot 39 KNMMW WW f v Team in 1913 from v n K e NEm 9500 g i Barbara L Welther I hemp W r j if 1982 Isis 73 94 E5 Z l g xxx 11 Tiom0 K E I L A J C Equot 6 39v 3 5 05 i A St WW MF w J ll ill 3 BAwe11es1ey1884 F J 2quot vi 1 5 WWW 1 i 1 a 13 5W j Pickering s assmtant r l l i 1 a f1 iv E i V a 3 mm 5 753000 K W 5W V I Mg F m W 0 Henry Draper w Fi w w FlI catalog of stars 35kmllgisiolf lug5gar a1ggglgtllll oo ssgo ilinlilnlinalii lllltll 4 4500 5 00 65 wavelength 9 wevumom 13gt Astronomer 1938 Very efficient Draper catalog has 250000 stars AJC 18631941 Stellar spectral types The H R Dlagram Wlth Slzes A Temperature Sequence Type Temperature 106 Ionized Neutral Hydrogen Ionized Neutral Molecules TIC O T helium hEIlLII39Tl metals quotHE39S B 1 104 g A 750010000 F 60007500 T 3 102 g G 50006000 3 K 35005000 g g M lt3500 g 100 b 139 J i 393 k 5 in K Spectra class F 10392 ExtraCredit for best OBAFGKM mnemonic 4 Huh 7 0 3 clicker points for entering 10 25 000 10 000 5 000 3 000 o 3 clicker points for 10 best answers that can be repeated in class 3 3 Temperature 3 3 Enter in Angel before Test 3 General Relativity The mathematical solutio Einstein on the happiest thought of my life I was sitting in the patent o ice at Bern when all Ufa sudden a thought occurred to e If a person falls freely he will notfeel his own weight The Principle of Equivalence I A thought experiment falling elevators 5 Upwards acceleration Falllng due No gavity no gravity to gavity Can t tell difference between gravity st acceleration or between freefall at no gravity So any experiment should give same answer in either case The Equivalence Principle at Work Tests Proofs of General Relativity I Bending ofsiarlight in Sun s gravitational eld Seen during 1919 eclipse W Wmmomur same thing with radio signals from Mars law you nsi New to a Tests Proofs of General Relativity I Precession ofMercury 190 degree per century in excess ofamount expected fro on s laws Easy to observe because oflong time span of observations GR predicts this Need extraplanet to explain it wit Newton s laws Mars Venus is too hot Why did Homework 3 is due 6am on greenhouse fail on Venus Wed the 18 Brief review Key Questions 1 What is the evidence that Mars has water 2 What is the evidence that Mars had liguid water at one time 3 Why did Mars become cooler so that liquid water disappeared 4 What is the evidence that Mars used to have a hot interior Goldilocks 1 Venus is too hot Mars is too cold Why is the earth just right not too cold and no too hot Venus is too close to the sun and Mars is too far This is part ofthe answer Re ected light is 2 d ingredient Greenhouse effect is 3 d ingredient Wthout he greenhouse effect earth would be 39ozen Mars has a small greenhouse effect Why did Venus evolve to have such a large greenhouse effect History is 4 relative to Wo GH Earth Table from Rampino ampCaldeira 1994 Ann Rev Astron ampAstrophys 32 p83 The faintsun paradox The sun was 30 fainter 3 Byrs ago The earth received 30 less sunlight but there was liquid water back then Why did the earth stayjust right not too cold and not too hot When the sun became brighter the earth became warmer More evaporation 3 more rain More rain 3 loss of more 002 sequestered in rock Less C02 3 less greenhouse effec Less greenhouse 3 Earth cools lessening effect of sun brightening When sun was fainter the earth was cooler Less evaporation 3 less rain 3 more C02 was released from rocks by volcanoes 3 more greenhouse effect 3 Earth warmed lessening effect of sun dimmin Walker Hays amp Kasting 1981 discovered this effect which provides negative feedback Why did greenhouse run amok on Venus Key observation 1 Earth s ocean has 100000 X more water than Venus atmosphere Deuterium Normal H has 1 proton in nucleus Deuterium D has 1 proton amp 1 neutron At the same temperature normal hydrogen gas moves faster than deuterium and is more likely to escape Key observation 2 on deuterium abundance On earth HD5000 On Venus HD50 Q4 Which hypothesis does KO2 support a Venus formed without much water b Venus lost its water On Jupiter HD45000 Over the history of Earth HD dropped to 5000 because it is easier for H to escape than D Earth has lost part of its hydrogen Since HD is hi her on Venus Venus has lost more of its hydrogen and t erefore its water Venus lost its water Venus is hotter because it is closer to sun Water was in atmosphere Ultraviolet light broke water into oxygen and hydrogen Hydrogen escaped No rain gt no way to get rid of 002 Models show Earth will suffer same fate if sunlight increases by 40 002 cycle will not be sufficient to keep Earth temperate S Mars ome of the 16 spacecraft that have gone to Mars Mariner 9 orbiter 197172 Viking 121anders 197680 Path nder lander rover 1997 Climate Orbitor Polar lander crashed 1999 Mars Global Surveyor orbiting Mars since March 1999 Odyssey orbiting Mars since October 2001 The Mars Rovers Searching for former lakes and oceans Opportunity Two separate missions Arrived January 2004 Can travel 40 metersday Have far exceeded planned 3 month mission Carry cameras spectrometers alphaparticle detector grindi 9 geology Meridiani Plain Hematite iron oxide rust deposits Former hot spring Gusev Crater Form er lake Bore hole Sites Dmm Mums MacKenzie k Alex Hmhavg Endurance Finding lots of Crater eVidence for water H in past at both sites 1 00 m l leridiaiii Planum Gusev Crater Geology Density suggests mostly silicates but small metal core No detectable magnetic eld Continental highlands 0 cover N 50 of planet Lowlying lava plains 0 average of 4 km lower than continents 0 Same age as lunar maria 34 billion yrs old Topographic Map From Mars Global Surveyor orbiter Red high areas Blue 10W areas Tharsis bulge uplifted continent 10 km high 0 has 4 huge volcanoes 15 km high Olympus Mons 500 km diameter would cover MI lower peninsula 25 km above surrounding plains largest mountain in Solar System 100 X volume ofMauna Loa lt 100 million yrs old impact crater counts so Mars is still geologically active Valles Marineris 5000 km long 14 way around Mars would stretch clear across US Huge tectonic crack in Tharsis bulge 810 km deep no outlet for water but some minor role of water erosion in side canyons Martian Atmosphere Pressure is low Very cold almost no liquid water At Mars low atmospheric pressure water should go straight from ice to vapor No Greenhouse effect because there is so little atmosphere Polar Ice Caps S them p Always below 1501 K 279 so co2 frozm all year Unknown mix of co2 and H20 Ice Only underlying H20 ice le in Northern Cap Climate change Used to be lots of running water Runoff channels From rainstorms billions of years ago Fig 722 What happened to Mars greenhouse At one time Mars was warm enough for liquid water C02 reacts with silicate rocks to convert to carbonate rocks Q5 Why is sequestering of carbon in rocks not fatal on earth a The rocks are protected by vegetation b Because of plate tectonics the carbon is released again c On earth this does not happen as much because of the C02 produced by volcanoes amp meteors Meteor bombardment ceased Bein smaller Mars cools faster amp volcanoes decrease more rapi y What happened to Mars Mars did have H20 amp C02 Where did H20 go H20 dissociates to 02 amp H2 by UV light Hydrogen escapes Oxygen reacts with rock gas by solar wind p articles Low temperature freezes water Fig 727 Gammy Ray Spectrometer amp Neutron Spectrometer on Mars Odyssey A 4 mp surface is well over 50 percent water ice by volume Ifjust the top meter ofice liquid water to ll Lake Michiganquot Boynton Water Map 2W Mars Odyi ey Gamma REY Spectrometer H20 Law quot H20 High 2005 Test Test1 2005 Answers on Syllabus Answerto Q19 was wro SOAR Telescope Cerro Pachon Chile Purpose Telescope collects amp focuses light onto a detector Light collectors Refracting telescope lens Using a lens refractor Reflecting telescope uses mirror Your eye is a telescope Lens is the lens Retina is the detector Using a mirror re ector Two goals Magnify amp gather light Magnifyimage to see ner detail Wavelength or llght D ls dlameteroflerls or mlrror Gather more light to see fainter objects Amount of ll ht ls proportlorlal to the area ofthe telescope Telescope diameteris key parame er SOAR ls a 47m telescope Gallleo s lrlrltelescope Q Your eye is a telescope Lo ok at your neighbor s eyeA 18quot B C1 IMss wnm Gallleu s telescupe With l lens Magnify amp gather light Magnify image to see ner detail Smallest detail is limited by wavelength oflight Smallest arlgle s MD A ls Wavelength or llght D ls dlameteroflerls or mlrror Gather more light to see 39ects fainter ob Amount of llght ls proportlorlal to the area ofthe telescope QZA hawk can see a My eye lstoo smallto etalls My eye lstoo smallto see the ralnt mouse See Small d o mlmss rerw Gallleu s telescupe With l lens large groundbased optical telescopes Lick 36quot Rerrzcmr 1888 3 7h Mtlemnar 2mquot Rd lectm 1948 Lightgathering power oc mirror diameter2 Technological advances Lenses mirrors Thick mirrors thin mirrors Passive support active Eumpeysv y Large Improved image quality 2 Scope Now working on designs for 30 FUN Sm E ESWPES m diameter telescopes Mirror fur Gemini 8111 T elescup e SOAR An International Pan 39 Why the southern hemisphere Remote Observing from MSU I he I elescope in dethe Dome 34nhTorop calpa 1 M2 14 feet diameter 4 h1c11qslttllick Ml Primary Mirror InStI llIH ant analy 26 5 light
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